Selina Concise Biology Class 7 ICSE Solutions – Nervous System

Selina Concise Biology Class 7 ICSE Solutions – Nervous System

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APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 6 Nervous System

Synopsis —

  • The interaction of these activities of a living being as per the needs of the body internally or externally is called coordination.
  • Nervous coordination is brought about by the nervous system which is made up of the brain, spinal cord, nerves and the sense organs.
  • Chemical coordination is brought about through chemical messengers called hormones.
  • The nervous system is made up of special cells called nerve cells or neurons.
  • The end of the axon terminates in a number of branches called terminal branches.
  • The terminal branches of the axon of one neuron lie very close to the dendrites of another neuron. This point of contact is called a synapse.
  • A nerve is formed of a bundle of axons (nerve fibres) enclosed in a tubular medullary sheath. There are three kind of nerves as describe
    1. sensory nerve
    2. motor nerve
    3. mixed nerve.
  • The nervous sytem of human beings consists of the following three systems:
    1. The central nervous system
    2. The peripheral nervous system
    3. The autonomic nervous system
  • The brain has three main parts:
    1. The cerebrum
    2. The cerebellum, and
    3. The medulla oblongata
  • The main functions of the spinal cord are:
    1. To control reflexes below the neck.
    2. To conduct messages from the skin and muscles to the brain.
    3. To conduct commands from the brain to muscles of the trunk and limbs.
  • The autonomic nervous system consists of a pair of chain of nerves and ganglia found on either side of the backbone.  This system controls the involuntary activities of the internal organs.
  • Stimulus: Any change in the environment that usually results in change in the activity of the body.
  • Response: The activity of the body in response to a received stimulus.
  • Impulse: A wave of electrical disturbance that runs through the nerves.
  • Receptors : These are sense organs which receives the stimulus.
  • Effector: Any muscle or gland where the response occurs.

Review Questions

Multiple Choice Questions:

1. Put a tick mark (✓) against the correct alternative in the following statements:

(a) Medulla oblongata controls
(i) Smelling
(ii) Beating of heart and respiratory movement
(iii) Intelligence and will power
(iv) Balancing the body

(b) Spinal cord is an extention of:
(i) Cerebellum
(ii) Cerebrum
(iii) Vertebral column
(iv) Medulla oblongata

(c) Body posture is mantained by:
(i) Cerebellum
(ii) Cerebrum
(iii) Medulla oblongata
(iv) Spinal cord

Short Answer Questions:

1. Write one word in the space provided to complete the second pair of the related words pertaining to nervous system.
Memory: cerebrum:: breathing:
Balance: cerebellum:: reasoning:
Answer:
Memory: cerebrum: beathing: medulla oblongata
Balance: cerebellum:: reasoning: cerebrum

2. (a) Name three major divisions of the human nervous system.
Answer:

  1. The central nervous system (brain and spinal cord)
  2. The peripheral nervous system
  3. The autonomic nervous system

(b) Name the three main parts of human brain.
Answer:

  1. Cerebrum
  2. Cerebellum
  3. Medulla oblongata

3. Given here is the diagram of a neuron. Name the parts numbered 1-6.
Selina Concise Biology Class 7 ICSE Solutions - Nervous System 1

Answer:

  1. dendrite
  2. dendrite (Terminal Arborization)
  3. nucleus
  4. axon (Nerve fibre)
  5. cell Body (cyton)
  6. node of ranvier
  7. sheath

Long answer questions

Question 1.
With the help of a suitable diagram describe the structure of a neuron.
Answer:
Selina Concise Biology Class 7 ICSE Solutions - Nervous System 2

Nervous system consists of special cells called nerve cells or neurons. It has a main cell body called cyton. It gives out many processes called dendrites. From it a very long process is given out. It is called axon or nerve fibre.

The cell body has a nucleus. The dendrites get the message from the organs and send this message to the axon through the cell body. Then the axon sends the message to muscles to contrast or to the gland for secretion.

The neurons make contact with one another through their processes. The axon at its end branches and meets the dendrites of another neuron. The meeting point is called synapse. The message is passed on from one axon to the dendrites of another neuron. How the message goes ? It is like this:
Organ → Message goes to dendrites →Cell body → Axon → Muscles or  glands

Question 2.
Briefly describe the structure of the cerebrum in human brain, and mention its functions.
Answer:
Brain consists of main three parts and lies in the cranial cavity of skull.

  1. The cerebrum
  2. The cerebellum
  3. The medulla oblongata

Cerebrum — It is very large and form two third of the whole brain. The two hemispheres are separated from each other by a deep longitudinal groove, the median fissure. The outer surface is folded with ridges and grooves. The hemispheres are hollow from inside and their walls have outer and inner portions. The outer portion has cell bodies of the neurons and it is called grey matter.
The wavery edges of the folded layer has large number of neurons to the extent of nine billion. The inner portion of the cerebrum has axons and it is called white matter.
Functions:

  1. It controls all the voluntary activities.
  2. It is the seat of intelligence, consciousness and will power.

Question 3.
Mention the three functions of spinal cord.
Answer:
Spinal cord has the following functions.

  1. It is the centre of reflex actions below the neck.
  2. It carries messages from the skin and muscles to the brain.
  3. All the stimuli and responses are passed from and to the brain through the spinal cord.

Question 4.
Describe three kinds of nerves, giving example of each.
Answer:
A nerve is formed by a group of nerve fibres (axons) encased
by tubular medullary sheath. The medullary sheath acts as insulation and do not allow mixing up of impulses of the neighbouring axons (nerve fibres) We have three kinds of nerves:

  1. Sensory nerve — It brings impulses from sense organs as these have sensory fibres. These nerve carry the impulses from the sense organs to the brain or to the spinal cord as optic nerve of the eye.
  2. Motor nerves—These carry impulses to muscles or glands from the brain or spinal cord. These nerves have only motor fibres as nerves to the muscles of the eye ball.
  3. Mixed nerve — It has both sensory and motors fibres as nerve going to the tongue.

Question 5.
What are voluntary and involuntary actions ? Which part of the nervous system controls them ?
Answer:
Voluntary action: When an action is produced with the involvement of thoughts, they are called the voluntary action. For example, writing an article jumping from heights. These actions are produced consciously by our body.
Involuntary action: Actions which take place without consciousness or willingness of an individual are called the involuntary action. Digestion, heart beating, sneezing, etc are few examples of involuntary actions.

  1. The cerebral cortex controls our voluntary actions like running and walking etc.
  2. Medulla helps in involuntary actions like hearbeat, breathing etc.

Additional Questions

I. Multiple choice questions. Tick (✓) the correct choice:

I. Nervous system in humans consists of
(a) brain and nerves
(b) brain and spinal cord
(c) brain, spinal cord and nerves
(d) none of the above.

II. Fill in the blanks:

  1. Basic structural unit of the nervous system is the neuron.
  2. Central nervous system consists of brain and spinal cord.
  3. A neuron consists of cell body, dendrite and axon.
  4. The neurons carrying impulses from the brain to the muscles are called motor or efferent neurons.
  5. Peripheral nervous system consists of nerves.
  6. The three main parts of the brain are cerebrum, cerebellum and medulla oblongata (brain stem).

III. State whether the following statements are true (T) or false (F):

1. Each neuron consists of three parts called cell body, cyton and axon.
 False. Each neuron consists of three parts called cell body, dendrite and axon.

2. The largest part of the brain is the cerebrum.
 True.

3. Cerebellum maintains balance of the body.
True.

4. There are 31 pairs of cranial nerves.
 False. There are 12 pairs of cranial nerves.

IV. Find the odd-one out, giving reasons:
Axon, cell body, dendrite, cerebellum
Ans. Cerebellum is the odd one out as it is a part of brain while rest three are parts of a neuron.

V. Define the following:
1. Reflex arc
2. Sensory neuron
3. Motor neuron
4. Neuron
Answer:

  1. Reflex arc: The path that an impulse takes in a reflex action is called a reflex arc.
  2. Sensory neuron: The neurons which carry impulses
    from the body parts to the spinal cord or the brain are called sensory or afferent neurons. For example, optic nerve of the eye.
  3. Motor neuron: The neurons which carry impulses from the brain or spinal cord to the body parts are called motor or efferent neurons.
  4. Neuron: A neuron or a nerve cell is the basic structural and functional unit of the nervous system.

VI. Answer the following:

Question 1.
 Describe the two parts of the nervous system.
Answer:
The nervous system of human has two parts:

  1. Central Nervous System (CNS): It consists of the brain and the spinal cord. The brain lies protected inside the skull while the spinal cord is protected within the vertebral column.
  2. Peripheral Nervous System (PNS): It consists of nerves arising from the spinal cord (spinal nerves) and the brain (cranial nerves). These nerves link the central nervous system with the various body organs.

Question 2.
What are nerves? Mention the types of nerves found in humans.
Answer:
A bundle of nerve fibres joined together as a tubular sheath that transmits impulses between brain or spinal cord and other body parts is called a nerve. The nerves constitute the peripheral nervous system.
Nerves are of two types in humans:

  1. Cranial nerves: They emerge from the brain. There are 12 pairs of cranial nerves.
  2. Spinal nerves: They emerge from the spinal cord. There are 31 pairs of spinal nerves.

Question 3.
Explain the structure of brain.
Answer:
The brain is the main control centre of the nervous system.
It is enclosed within the bony shell of cranium.
It consists ofthree main part:

    1. Cerebrum: It is the uppermost and largest part with many ridges and grooves. It is divided into right and left halves called cerebral hemispheres. It controls our thinking, reasoning, intelligence, memory and perception of pain, sound, touch, taste and smell.
    2. Cerebellum: It is located under the cerebrum at the back of the head. It maintains balance of the body and coordinates muscular activity.
    3. Brain stem (medulla oblongata): It joins the brain to the spinal cord. It controls the activity of internal organs like heartbeat and breathing.
      Selina Concise Biology Class 7 ICSE Solutions - Nervous System 3

Question 4.
Compare the nervous system and the endocrine system.
Answer:
Nervous system

  1. Messages are sent through nerve fibres.
  2. It consists of brain, spinal cord and nerves.
  3. No hormones are secreted. Messages are sent as impulses.
  4. Transmission of impulse is quick.

Endocrine system

  1. Messages are sent through blood in the form of hormones.
  2. It consists of endocrine glands.
  3. Hormones secreted by glands regulate the body activities. .
  4. Transmission takes time.

Selina Concise Biology Class 7 ICSE Solutions – Photosynthesis and Respiration

Selina Concise Biology Class 7 ICSE Solutions – Photosynthesis and Respiration

ICSE SolutionsSelina ICSE SolutionsML Aggarwal Solutions

APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 4 Photosynthesis and Respiration

Synopsis —

  • The process of preparing or synthesising food using water from the soil and carbon dioxide from the air, together chlorophyll and sunlight is called photosynthesis.
  • Photosynthesis occurs in the mesophyll cells of the leaf. These cells contain numerous plastids called chloroplasts.
  • With in the plastids is present the green pigment called chlorophyll.
  • On the lower surface of the leaf are numerous pores called stomata, which open into small air cavities inside the leaf.
  • Stomata are tiny openings found mainly on the lower surface of leaves. These openings are surrounded by a pair of bean¬shaped cells called guard cells.
  • All plants have a transport system called vascular system. It is composed of two types of tissues called xylem and phloem.
  • There are two end-products of photosynthesis :
    • Glucose (C6H12O6)
    • Oxygen
  • The energy released during respiration is stored as chemical energy in the form of ATP — adenosine tri-phosphate.
  • Aerobic respiration —
    C6 H12O6+6O2  →  6CO2+6H2O+38ATP
    Anaerobic respiration —
    C6H12O6 →  2C2H5OH+2CO2+2ATP
  • During vigorous exercise, the cells respire anaerobically and form lactic acid which accumulate in the muscle cells causing fatigue and pain.
  • Cellular respiration is called internal respiration which takes place in the cells of living organisms.
    Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 1
  • The frog respires through
    1. skinmouth
    2. lining
    3. lungs.
  • The respiratory organs of the fish are gills.
  • Transpiration is the loss of water in the form of water vapour from the aerial parts of the plant.
  • Transpiration occurs through stomata.
  • The factors which affect the rate of transpiration are 
    1. Sunlight
    2. Temperature
    3. Wind
    4. Humidity
  • The significance of transpiration
    •  Maintain the concentration of the sap inside the plant body.
    • Causes cooling effect

Review Questions

Multiple Choice Questions
1. Put a tick (✓ ) against the most appropriate alternative in the following statements.
(i) Carbohydrates are stored by plants in the form of:
(a) Vitamins
(b) Proteins
(c) Fats
(d) Glucose 

(ii) Stomata are present on the surface of:
(a) Leaves
(b) Roots
(c) Stem
(d) Flower petals

(iii) Which one of the following is an end-product of photosynthesis ?
(a) Fructose
(b) Glucose
(c) Cellulose
(d) Lactose

Short Answer Questions

1. Why do leaves generally look green ?
Answer:
The green colour of a leaf is due to the presence of chlorophyll.

2. Which four of the following are needed for photosyn-thesis in a leaf:
(i) Carbon dioxide:
(ii) Oxygen:
(iii) Nitrates :
(iv) Water:
(v) Chlorophyll:
(vi) Soil:
(vii) Light:
Answer:
(i) Carbon dioxide: from air
(iv) Water: from soil
(v) Chlorophyll: contained in leaf
(vii) Light: from sunlight

3. What is the source of energy for photosynthesis ?
Answer:
Light is the ultimate source of energy in photosynthesis because plants take in the sunlight CO2 and H2O and converts it into glucose.

4. Which gas is taken in and which one is given out by the leaf in bright sunlight ?
(i) Taken in :
(ii) Given out:
Answer:
(i) Carbon dioxide
(ii) Oxygen

5. Suppose we compare the leaf with a factory, match the items in Column A with those in Column B.
ColumnA Column B
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 2

Answer:
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 3

6. State whether the following statements are True or False:

(i) Green plants prepare their food by using two raw materials, oxygen and water.
False. Green plants prepare their food by using raw materials, CO, chlorophyll and water.
(ii) The chlorophyll enables the plants to use light energy.
 True
(iii) The free oxygen in the atmospheric air is the result of photosynthesis.
 True
(iv) Photosynthesis occurs only in chlorophyll-containing parts of the plant.
True

7. Differentiate between aerobic and anaerobic respiration. Write the overall chemical equations of the two kinds of respiration in plants.
(i) Aerobic:
(ii) Anaerobic:
Answer:
Aerobic respiration

  1. It occurs in the presence of oxygen.
  2. Here there is complete breakdown of glucose releasing carbon-di-oxide, energy. water and energy.
  3. More energy is released (38 ATP).

Anaerobic respiration

  1. It occurs in the absence of oxygen.
  2. There is partial breakdown of glucose into ethyl alohol, carbon-di-oxide and
  3. Lesser energy is released (2 ATP).

(i) Aerobic respiration:
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 4
(ii) Anaerobic respiration:
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 5
Question 8.
 Explain how photosynthesis is different from respiration.
Answer:
Photosynthesis

  1. Anabolic process
  2. Food is produced here.
  3. Oxygen is by-product.
  4. Chlorophyll and sunlight are required.
  5. Occur only during daytime.
  6. Occurs in green plants only.

Respiration

  1. Catabolic process
  2. Food is broken down form here to release energy
  3. Carbon-di-oxide is the by-product.
  4. Chlorophyll and sunlight are notrequired.
  5. Occurs all the time
  6. Occurs in all living beings including plants.

Photosynthesis :
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 6

Respiration:

C6H12O6+6O→6CO2+6H20+energy

Question 9.
 Do the plants respire all day and night or only during the night ?
Answer:
The plants respire only during the night. Plants take in oxygen and give out carbon dioxide. Hence, there is some truth in the belief that one should not sleep under the trees at night.

Question 10.
 What happens to the energy liberated during respiration?
Answer:
The energy liberated during respiration is utilised for carrying out various life processes.
Some of the energy liberated during the breakdown of 03 the glucose molecule, is in the form of heat, but a large part of it is converted into chemical energy called Adenosine Triphosphate (ATP). Any activity inside the cell is carried out by the energy released by these ATP molecules.

Long Answer Questions

Question 1.
In order to carry out photosynthesis, what are the substances that a plant must take in ? Also mention their sources.
Answer:
For preparing food, the plants require the following :

  1. Water (from soil)
  2. Carbon dioxide (from air)
  3. Chlorophyll (contained in the leaf)
  4. Energy (from sunlight)

The process of preparing or synthesising food using water from the soil and carbon dioxide from the air, together chlorophyll and sunlight is called photosynthesis. This entire process is a series of complex chemical reactions Photosynthesis is represented as follows:
Selina Concise Biology Class 7 ICSE Solutions - Photosynthesis and Respiration 7

Question 2. 
What is the role of chlorophyll in photosynthesis ?
Answer:
This pigment is of utmost importance as it absorbs the sunlight which provides energy for the process of photosynthesis occurs inside the chloroplast of the leaf.

Question 3.
Do plants need oxygen ? If so, what is its source ?
Answer:
Yes plants need oxygen, all the free oxygen in the atmospheric air is the result of photosynthesis. No animal can survive without oxygen as it is needed for respiration. Even the plants use the same oxygen in dark for their own respiration.

Selina Concise Biology Class 7 ICSE Solutions – Classification of Plants

Selina Concise Biology Class 7 ICSE Solutions – Classification of Plants

ICSE SolutionsSelina ICSE SolutionsML Aggarwal Solutions

APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 2 Classification of Plants

Synopsis:

  • Classification means grouping things together on the basis of certain common features.
  • The classification helps us to identify the living organisms and to study them more easily and systematically.
  • The plants can be classified as follows on the basis of their size and shape as:
    1. Herbs
    2. Shrubs
    3. Trees.
  • The plants which have soft, green and perishable stems are called herbs.
    Example: maize, rice, mint etc.
  •  The plants with woody stems, with branches of almost equal size arising from the stem immediately above the soil are called shrubs.
    Example: Lemon, jasmine etc.
  • The plants which are tall and have hard, woody stems and bear woody branches, twigs and leaves at some distance above the ground are called trees.
    Example: Coconut and palm.
    Non – flowering plants are called Cryptogams
  • Flowering plants are called Phanerogams.
  • The non-flowering plants can be further classified as:
    1. Thallophyta (Bacteria, Fungi and Algae)
    2.  Bryophyta (Mosses)
    3. Pteridophyta (Ferns)
  • Thallophyta do not bear-roots, stems or leaves.
  • Mosses have stems and leaves but no roots rather have
    thread-like structures called rhizoids.
  • Mosses are called Amphibians of the plant group as they need water to reproduce.
  • Spores are not seeds.
  • Spores are tiny structures capable of producing new plants.
  • The flowering plants can be further classified into
    1. Gymno sperms.
    2.  Angiosperms.
  • The flowering plants that bear seeds but no fruit are called Gymnosperms. Their seeds are thin and naked.
  • The characteristic feature of gymnosperms is that their roots are well developed, trunk is thick and woody and their leaves are long and pointed.
  •  The female part of the angiosperms plant is called ovary.
  •  The plants can be classified on the basis of life span as:
    1. Annuals
    2. Biennials
    3. Perennials
  •  The plants which live for only one season in a year are called annuals.
    Example: Wheat, rice, pea, sunflower.
  •  The plants which complete their life cycle in two years, i.e. in the first year they bear the vegetative parts while in the second year they bear flowers, fruits and seeds are called
    biennials.
    Example: Carrot, potato, cabbage.
  •  The plants which live for more than two years and bear flowers, fruit and seeds every year.
    [They may even live for hundreds of years] are called
    perennials.
    Example: Banyan, pine.
  • The perennial plants can be further divided as
    1.  Deciduous: Shed their leaves once in a year usually before winter. •
      Example: Oak, mulberry.
    2. Evergreen: These never shed their leaves all at one time. They keep shedding their leaves throughout the year. Example: Mango, guava etc.
  • The self – nourishing living beings are called autotrophs. Those nourishing on others are called heterotrophs.
  •  On the basis of habitat, the plants can be classified as.
    1. mesophytes
    2. xerophytes
    3. hydrophytes.
  •  Mesophytes : The plants which grow on land and need moderate amount of water for their survival.
    Example: Mango,apple.
  • Xerophytes:

    1.  The plants which grow is deserts and need minimum amount of water for their survival.
    2.  These have thin and spiny leaves to minimise water loss.Example: Cactus, Babul etc.
  • Hydrophytes:
    1. The plants need maximum amount of water and hence grow in water.
    2.  They have either very small or no roots at all.
      Example: Lotus, water lily etc.

Activity 1
Visit a garden park with your teacher or parents and take along with you, a notebook and a pencil. In the park, you would see a large variety of plants some very small, some with average height and some very tall. These plants differ in their features like shape, size (small/medium/tall) and life span. Observe these features carefully (you may even take help from the Gardner) and note down in the table given below.
Classify these plants in their respective appearance and categories:
Answer:
Selina Concise Biology Class 7 ICSE Solutions - Classification of Plants 1

Activity 2
Visit a nearby garden or park. Observe the different types of plants small and large, growing there. If permitted by the care-taker collect samples of as many types of plants as you can by plucking. Be sure that you do not damage the plant and collect only one specimen of each type. Take them to your school and record them according to their categories in your notebook
Answer:
Selina Concise Biology Class 7 ICSE Solutions - Classification of Plants 2 

Activity 3

You will see two parts in gram seed. Each part of the seed in called cotyledon. In maize seed, you will see only one cotyledon. Can you tell which seed among them is monocotyledon and which is dicotyledon ?
Monocot : Dicot
Answer:
Monocot: maize seed Dicot: gram seed

Review Questions 

1.Tick (✓) the appropriate answer :

(i) The two main categories of plants recognised on the basis of whether they produce fruits or not:
a) Biennials and annuals
b) Angiosperms and gymnosperms
c) Herbs and shrubs
d) Bryophyta and pteridophyta

(ii) Unicellular organisms with a proper nucleus are known as :
(a) Protista
(b) Monera
(c) Fungi
(d) Algae

(iii) Amoeba belongs to :
(a) Monera
b) Protista
(c) Fungi
(d) Algae

Short Answer Questions

1. Name the categories of the following:

  1.  Plants which do not have roots, stems, and leaves: Thallophyta.
  2.  Plants with no roots, but have stems and leaves: Bryophyta  or Mosses.
  3.  Plants with roots, stems, and leaves, and which bear spore- producing bodies: Pteridophyta or Ferns.
  4.  The amphibians of the plant kingdom mosses (Bryophytes)

2. Give two characterists and one example of each of the following:

(i) Algae:
Ans. Example: Spirogyra
(a) these are found in stagnant water of ponds, growing as green scum
(b) they have chlorophyll

(ii) Fungi:
Ans. Example: Mushroom
(a) They cannot prepare their food
(b) Most fungi live on dead and decaying organic matter

(iii) Monocot:
Ans. Example: Maize
(a) They have seeds with one cotyledon
(b) Cotyledon usually becomes the embryonic first leaves of a seedling

(iv) Dicot
Ans. (a) They contain two cotyledons in their seed.
(b) They have network like (reticulate) venation in their leaves.
Examples : gram, rose, mango.

(v) Bryophyta
Ans. (a) They have stems and leaves but no roots.
(b) They are non-flowering plants.
Examples : mosses, liverworts.

(vi) Pteridophyta
Ans. (a) They are non-flowering plants i.e. do not produce flowers are seeds. They reproduce through spores
(b) They have feather like leaves divided into leaflets. Example : ferns

(vii) Thallophytes
Ans. (a) These plants do not have roots, stems or leaves.
(b) They are non-flowering plants.
Examples : Bacteria, fungi, algae

3. Differentiate between

(i) Algae and fungi

Algae

  1.  Usually green having chlorophyll
  2.  Found in stagnant water of ponds.
  3.  Are usually Autotrophs e.g. Spirogyra

Fungi

  1. Do not have chlorophyll
  2. Found on dead and decaying organic matter.
  3. Are usually saprophytes. e.g. Bread mould

(ii) Monocot and dicot plants.

Monocot
The plants which contain only one cotyledon in their seeds.
example: Grass, Maize

Dicot
The plants which contain two cotyledons in their seeds.
example: Brinjal, Mango

(iii) Autotrophs and heterotrophs

Autotrophs

  1. They can make their own food using solar energy.
  2.  These include green plants having chlorophyll.
  3.  They are also called producers.

Heterotrophs

  1. They cannot make their own food and depend on autotrophs or other heterotrophs for food.
  2. These include animals and non-green plants.
  3. They are called consumers.

(iv) bacteria and amoeba

Bacteria

  1. Bacteria are one of the smallest and structurally the simplest organisms.
  2.  Bacteria are unicellular cells
  3.  They are found every-where air, water, soil, the bodies of humans, plants and animals.
  4.  They are visible only under a high powered light microscope

Amoeba 

  1.  Amoeba is one of the simplest animals.
  2. It is made up of just one single cell.
  3. Amoeba is found in ponds, ditches and other places with stagnating water.
  4.  They can be seen under the microscope only

(v) mosses and ferns
mosses

  1.  Mosses grow as green, velvety layers in moist places such as damp soil, on the bark of trees, and on damp walls.
  2. These plants have stems and leaves, but no roots

ferns

  1.  Ferns are grown in most of the gardens for their beautiful leaves.
  2. They bear well-formed leaves, stems and roots.

(vi) Angiosperms and gymnosperms
Angiosperms

  1. These plants bear seeds inside a fruit.
  2.  Leaves are usually broad.
  3. They usually shed their leaves every autumn.
  4. Examples: rose, sunflower, sugarcane.

gymnosperms

  1. These plants bear naked seeds called cones. Fruit is absent.
  2.  Leaves are usually needle like. They usually remain green throughout the year.
    Examples: Pine, cedar, fir.

Long Answer Questions
(Write the answers in your note book)

Question 1.

What name is given to bacteria found in the root nodules of pea plants ? State their importance.
Answer:
Rhizobium bacteria are found living in the root nodules (small swollen structures on roots) of leguminous plants like the pea, bean etc. These bacteria trap the nitrogen from the atmosphere and convert it into nitrates (mineral salts) which can be easily absorbed by the plants from the soil along with the water. It is observed here that the bacteria provide food to the host plant and the host plant in turn provides shelter for the bacteria. This kind of relationship wherein two organisms live in harmony each benefiting from such a relationship is called symbiosis. The organisms are called symbionts.

Question 2.
Briefly explain four types of bacteria on basis of their shape.
Answer:
There are four common forms of bacteria – coccus, bacillus, spirillum and vibrio.

  1. Coccus form: These bacteria are spherical or ovoid in shape.
  2. Bacillus form (bacillus : rod) These are rod-shaped. These may also occur singly or in group of two’s or three’s, joined end to end in long chains.
  3. Spirillum form: These are spiral-shaped.
  4. Vibrio form: These are short, curved, appearing comma- shaped. Chloera bacteria (Vibrio cholerae) are of vibrio type.

 Question 3.
Give reasons for the following:

(i) Bryophytes are called amphibians of plant kingdom.
(ii) Amoeba does not have any regular shape.
Answer:

  1. Since bryophytes grow on land but need water for reproduction (like frogs in animals), they are called the amphibians of plant kingdom.
  2. The body of Amoeba is irregular in shape. The outer covering of the body is the cell membrane. A prominent nucleus lies in the center surrounded by cytoplasm.

Question 4.
What is a contractile vacoule ? State its function in amoeba.
Answer:
Excess of water from the body of the amoeba is collected in the contractile vacuole. Ammonia is soluble in water. Hence, sometimes ammonia is expelled out along with the water from the contractile vacuole.
Function: The contractile vacuole expands when there is water in it and shrinks when the water is released into the surrounding.

Question 5.
List out Jive uses each of bacteria and fungi in our lives.
Answer:
The uses of Bacteria are :

  •  Lactobacilus bacteria is used for curdling of milk (formation of curd from milk). It converts the milk sugar (lactose) into lactic acid, giving the sour taste to the curd.
  •  Certain bacteria like Acetobacter ferment fruit juices into vinegar (acetic acid).
  • Tanning of leather: Certain bacteria are used in curing of animal hides and skin.
  • Retting of fibres: Jute fibres are separated and made softer by the use of bacteria.
  • Formation of compost and manure: Cow dung, horse dung and agricultural wastes are subjected to bacterial action which causes their decay and produce very useful manure.

The uses of Fungi are:

  • Fungi are an important source of food. Some mushrooms such as Morechella and Agaricus are edible.
  • Yeast, a unicellular fungus, is important in bakeries as it is used in the making of bread. It is also important in the breweries for making alcohol.
  • Yeast also produces vitamin B.
  • Fungi, like bacteria, are also good decomposes. They decompose dead organic matter and return the nutrients back into the soil.
  • Penicillin an important antibiotic is obtained from a fungus called Penicillium notatum.

 

Selina Concise Biology Class 7 ICSE Solutions – Excretion in Humans

Selina Concise Biology Class 7 ICSE Solutions – Excretion in Humans

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APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 5 Excretion in Humans

Synopsis —

  •  The substances which should be excreted are :
    1. urea, uric acid
    2.  Bile pigments
    3. water
    4. extra salts such as sodium
    5. chloride extra vitamins.
  • The vitamins passed out into urine if in excess are vitamin B and C.
  •  The kidneys are situated towards the back of the abdomen at the level of last two ribs.
  •  Right kidney is located at slightly lower level than the left kidney.
  • The ureters run from the kidney to the urinary bladder and urethra runs from urinaiy bladder to the exterior.
  • Accessory excretory organs are
    1.  skin
    2. lung
    3. liver
  •  The main function of the skin is to cool the body.
  •  Liver converts highly toxic ammonia produced in the body to less toxic urea.
  •  Liver eliminates cholesterol, bile pigments, extra vitamins, and many durgs.
  •  The amount of urine produced by the glomerular filtrate after reabsorption per day is 1.2 litre.

(Review Questions)

MULTIPLE CHOICE QUESTIONS :
1. Put a tick mark (✓) against the most appropriate alternative in the
following statements :

(i) The kidneys are made up of tiny tubular units called :
(a) glomerulus
(b) nephrons
(c) capillaries
(d) neurons

(ii) In human beings, urea is produced in :
(a) liver
(b) kidney
(c) spleen
(d) urinary bladder

(iii) Besides water, the urine mainly contains :
(a) urea
(b) nitric acid
(c) glucose
(d) bile pigments

(iv) Filtration of excretory wastes from the blood occurs in:
(a) collecting tubule
(b) ureter
(c) urinary bladder
(d) nephrons

Short Answer Questions
1. Fill in the blanks :

  1. Nitrogenous wastes in the urine are in the form of urea and uric acid.
  2. The unit of human kidney is called nephron.
  3.  Evaporation of sweat from skin surface has cooling effect.

2. Define the following:
(i) Excretion:
(ii) Excretory organs :
(iii) Dialysis :
(iv) Nephron:
Ans.
(i) Excretion :
During different metabolic activities taking place in our body, the body produces many substances of which some are useful and some are useless.
The process of removal of useless and harmful metabolic waste substances is called excretion.
(ii) Excretory organs : During different metabolic activities taking place in our body, the body produces many substances of which some are useful and some are useless.
If retained in the body the unwanted substances may become poisonous and cause much harm and in severe cases, even death. The organs which remove these unwanted and toxic substances from the body are called excretory organs.
(iii) Dialysis : The artificial process which cleans and filters the blood in a person where one or both the kidney may stop working properly is called dialysis.
(iv) Nephron : Inside the kidney, there are millions of microscopic tubes called renal tubules or nephrons. It is the structural and functional unit of kidney.

3. Write True (T) or False (F) for the following statements in the spaces provided. Rewrite the false statements in correct form.

  1. Removal of solid undigested food is excretion
    False
    Correct: Removal of solid undigested food is egestion.
  2.  Medulla of kidney passes urine into urinary bladder.
    False
    Correct: Medulla of kidney passes urine into funnel-like pelvis.
  3.  Excess sugar in blood is a symption ofdiabetes.
    True
  4.  Urine is devoid of blood cells.
    True

4. Name the blood vessel that brings blood to the kidneys.
Ans. Renal Artery

5. Where in the urinary system do the following processes take place ?
Ans.

  1. Urine formation: kidneys.
  2.  Transport of urine away from kidney: urethra.
  3.  Temporary storage of urine : urinary bladder.

Long Answer Questions

Question 1.
Define excretion. Write the four organs of human urinary system in their correct sequence.
Answer:
The process of elimination of unwanted and toxic products from the body is called excretion.
The four organs of the urinary system from above to downward are:

  1. kidneys
  2.  ureter .
  3. urinary bladder
  4.  urethera.

Question 2.
Why is excretion necessary in living beings ?
Answer:
The excretion is necessary because the toxic products if allowed to be retained in the body act as poison and cause great harm to the body. If they exceed the threshold, they may even cause death.

Question 3.
What is meant by osmoregulation ?
Answer:
The process of maintaining accurate concentration of water and salts in the body is called osmoregulation.
This is done by the kidneys.

Question 4.
Describe the structure of kidney with the help of a labelled diagram.
Answer:
Selina Concise Biology Class 7 ICSE Solutions - Excretion in Humans 1

Section through the kidney to show different regions The kidneys is composed of:

  1.  an outer darker area called Cortex
  2.  an inner lighter area called Medulla.

The microscopic structure of kidney is formed of millions of tubules called renal tubules or nephrons.

Question 5.
What are the two ways by which a person can get relief in case of kidney failure ?
Answer:
The two ways by which a person can get relief in case of kidney failure are:

  1. Dialysis: this is a method in which an artificial machine cleans and filters the blood.
  2.  The patient can undergo kidney transplant.

Question 6.
Draw a diagram of human excretory system and label the following parts : Kidney, ureter, urinary bladder and urethra.
Answer:
Selina Concise Biology Class 7 ICSE Solutions - Excretion in Humans 2

Question 7.
How are kidney stones formed ?
Answer:
Kidney stones are formed when crystal forming substances such as calcium oxalate, calcium phosphate and uric acid are
more than the fluid in the urine. When these chemicals start sticking together, they from crystals, commonly called kidney stones. They may be formed and cause severe plain.

Question 8.
What are the symptoms of an urinary tract infection ?
Answer:
 Common symptoms include a strong and frequent urge to urinate, and a painful and burning sensation while urinating.

 

Selina Concise Biology Class 7 ICSE Solutions – Allergy

Selina Concise Biology Class 7 ICSE Solutions – Allergy

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APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 7 Allergy

Review Questions

Question 1.
Define the term “allergy”.
Answer:
Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to something in the environment that usually causes no adverse effects to most people. These diseases include hay fever, dermatities, asthma, food allergies, etc.

Question 2.
Name the inflammatory chemical released by the basophils causing skin reaction and construction of the bronchioles.
Answer:
The histamine causes inflammation, skin rash and constriction of the bronchioles (as in asthma).

Question 3.
How the allergy causing chemical is naturally removed from the body ?
Answer:
There are no permanent cure for an allergy. Medication for allergies do give relief. Those people prone to allergic reactions should be aware of the allergens that trigger these responses in their bodies and avoid them completely, especially food and medicines. Allergy shots are helpful to those with seasonal allergies like those caused by pollen.

4. Match the items given under column I with those given under column II.
column I                                         column II
Selina Concise Biology Class 7 ICSE Solutions - Allergy 1
Answer:
              column I                                         column II
Selina Concise Biology Class 7 ICSE Solutions - Allergy 2

Question 5.
Name any three routes of which allergens normally enter in our body.
Answer:

  1. Skin — Substances that come into contact with the skin, such as latex, are also common causes of allergic reactions, known as contact dermatitis or eczema.
  2. Mouth — A wide variety of foods can cause allergic reactions, but 90% of allergic responses to foods’are caused by cow’s milk, soy, eggs, wheat, peanuts, tree nuts, fish and shellfish.
  3. Nose — Pollen, spores, dust particles and certain chemicals find entry through the nose.

Question 6.
What are allergens ? Name any three allergens.
Answer:
The substances that cause allergies are called allergens.

  1. Dust particles
  2. Nuts
  3. Pollen

Question 7.
Name the two tests generally used to diagnose allergy and describe any one of them.
Answer:

  1. Prick Test—Skin prick test is also known as “puncture testing” or “prick testing” due to the series of tiny punctures or pricks made into the patients skin. A small plastic or metal device is used to puncture or prick the skin. Sometimes, the allergens are injected intradermally into the patients skin, with a needle and syringe. Small amounts of suspended allergens or their extracts (e.g., pollen grain, insect sting proteins, peanut extracts) are introduced to sites on the skin marked with pen or dye. Common areas for testing include the inside of forearm and the back.
  2. Blood Testing — A sample of the patient’s blood is sent to a laboratory for analysis. Multiple allergence can be detected with a single blood sample.
    The test measures the concentration of specific antibodies in the blood. The quantitative allergy blood result can help determine what a patient is allergic to, help predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity.

Question 8.
Which test is mostly favoured for testing allergy, prick test or blood test ? Why ?
Answer:
Blood test is mostly favoured for testing allergy.

Blood Testing — A sample of the patient’s blood is sent to a laboratory for analysis. Multiple allergence can be detected with a single blood sample.
The test measures the concentration of specific antibodies in the blood. The quantitative allergy blood result can help determine what a patient is allergic to, help predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity.

Selina Concise Biology Class 7 ICSE Solutions – Plant And Animal Tissues

Selina Concise Biology Class 7 ICSE Solutions – Plant And Animal Tissues

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A PlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 1 Plant And Animal Tissues

Synopsis

  • The unit of level of organisation is independent in its mode of existence and activity.
  • All multi cellular organisms start their life as a single cell.
  • Plant tissues are basically of two type
    1.  meristematic
    2.  permanent or non-dividing
  • The permanent – plant tissues are further of three types
    1. protective
    2. supportive: parenchyma, collenchyma, sclerenchyma
    3. conductive: xylem, phloem
  • Parenchymal cells have thin-walled cells and usually with a vacuole.
  • Potatoes mainly are composed of parenchymal cells.
  • Collenchyma are parenchymatous cells which are elongated and are thick at the comers. This helps to support the parts of the plant.
  • Sclerenchyma tissue is formed of long, narrow and thick cells. This provides strength to the plant parts.
  • Xylem is formed of thick-walled, tubular and often dead cells. They transport water and minerals absorbed by roots.
  • Old xylem forms the wood.
  • Phloem is formed of living tubular cells which provide a passage for the downward transport of food.
  • The four major groups of animal tissues

    1. epithelial tissue
    2. connective tissue
    3. muscular tissue
    4. nervous tissue
  • The epithelial tissue is further of four types:

    1. squamous epithelium (protective)
    2. cuboidal epithelium (absorption)
    3. columnar epithelium (secretory)
    4. ciliated epithelium (movement of substances)
  • Supportive connective tissue consists of
    1. Cartilage
    2.  Bone
  • Fibrous connective tissue:
    It packs and binds most of the organs. It is of the following types.

    1. areolar tissue: binds skin to underlying tissue.
    2. adipose tissue: filled with fat.
    3. tendon: connect muscles to bones.
    4. ligaments: connect bone to another bone.
  • Fluid connective tissue consists of
    1. Blood
    2. Lymph
  • The liquid part of the blood is called plasma and the cellular part includes:
    1. red blood cells
    2.  white blood cells
    3.  platelets.
  • Three distinct kinds of muscles are
    1. striated or skeletal
    2. unstriated or smooth
    3. cardiac or heart.
  • A nerve cell is formed of a cell body called cyton and one or more elongated hair-like extensions called dendrites. The longest dendrite is called axon.
  • Systems of the body with their primary vital function.Skeletal system: support and protection
    1. Muscular system: movement
    2. Digestive system: nutrition
    3. Respiratory system: exchange of gases
    4. Circulatory system: transport of materials
    5. Excretory system: waste removal
    6. Nervous system: sensation and co-ordination
    7.  Reproductive system: continuation of race.

Review Questions

MULTIPLE CHOICE QUESTIONS

1. Put a tick (✓) against the most appropriate alternative in the following statements.

(i) A group of similar cells to perform a specific function forms a
(a) organ
(b) species
(c) organ system
(d) tissue

(ii) The fine branches given out from the cell body of a nerve cell are
(a) dendrites
(b) cyton
(c) axon
(d) neurons

(iii) Fluid connective tissue of humans is
(a) blood and cartilage
(b) lymph and plasma
(c) blood and lymph
(d) stroma and matrix

Short Answer Questions

Question 1.
1. Define the following terms:

  1. Tissue
  2. Organ

Answer:

  1. Tissue: A group of similar cells which perform a specific function.
    example: Muscular tissue in animals.
  2. Organ: The different type of tissues which group together to function in a co-ordinated manner.
    example: liver

2. Answer the following:

Question 2(i).
What is a meristematic tissue ? How is it different from permanent tissues ?
Answer:
Plant tissues are classified into two types:

  1. Meristematic tissue
  2.  Permanent or non-diving tissue

Meristematic tissues are the plant tissues which are made up of actively dividing cells. These tissues actively divide and lead to the growth of the plant body. They are found at the growth points of the plant like tips of root, stem and branches etc.

  1. Cells are small with thin cell walls.
  2. Cells have large and conspicuous nuclei.
  3. Cells have no vacuoles.
  4. Cells are actively dividing type cells.

Difference between Meristematic and permanent
Meristematic tissue :

  1. Meristematic tissue is present at the tip of the root and stem and in between the xylem and phloem. Form apical meristematic tissue when present at the tips. It is in the form of cambium in between the xylem and phloem.
  2. Meristematic cells divide and form other types of tissues. The cells are thin walled.
  3. Meristematic cells may be intercalary as in case of monocots.
  4. The cells are small and isodiametric, vacuoles are small or absent.
  5. Respiratory and biosynthetic activities maximum.
  6. The cells are immature and mitochondria simple.
  7. Proplastids act as plastids.

Permanent tissue

  1. Permanent tissue may be simple as parenchyma, collenchyma or sclerenchyma and it may be complex as xylem and phloem.
  2. These are made up of more than one kind of cells. These perform a common function Xylem and phloem form vascular system of the plant. These cells do not have the power to divide.
  3. These cells may act as epidermis cortex or grit cells. Sclerenchyma gives strength.
  4. Living cells of permanent tissue have vacuoles. The cells are large and of different shapes.
  5. Both these activities are low.
  6. The cells fully mature, mitochondria fully developed.
  7. Living cells have plastids.

Question 2(ii).
Which living material would you take to demonstrate meristematic tissue ?
Answer:
Green gram seeds can be used to demonstrate meristematic tissue which when soaked in a petridish stuffed with wet cotton and left for 3-4 days would sprout out. These sprouted seeds have roots developing whose root tips have meristematic tissue.

Question 2(iii).
What is the function of meristematic tissue ?
Answer:
The meristematic tissue have the primary role in the growth of the plant tissue as it consists of active dividing cells

Question 3.
State whether the following statements are True or False. 

(i) A tissue is formed of only one type of cells.
Ans. True

(ii) Only one type of tissue forms an organ.
Ans. False.
Correct: Two or more types of tissue form an organ.

(iii) Permanent tissue is made up of undifferentiated and dividing Cells.
Ans. False.
Correct: Meristematic tissue is made up of undifferentiated and dividing cells.

(iv) Meristematic tissue is found at growing tips of a plant.
Ans. True

(v) Phloem is formed of dead tubular cells.
Ans. False.
Correct: Phloem is formed of living tubular cells.

Question 4.
Fill in the blanks by selecting suitable words from the list given below:
“Thin – walled, collenchyma, vascular, tissues, conducting”

  1. A group of different tissues working together to perform a function is called an organ.
  2.  Xylem and phloem form the conducting tissue.
  3.  Conducting tissue is also called vascular tissue.
  4. Cells are elongated and thick at the comers in collenchyma tissue.
  5. Parenchyma is composed of large thin-walled cell

Question 5.
Match the items given is column A with those given in 
column B:

Column A
(i) Fibrous connective tissue
(ii) Fluid connective tissue
(iii) Supportive connective tissue
(iv) Ligament
(v) Tendon
Column B
(a) blood
(b) cartilage
(iii) Supportive connective tissue
another bone.
(d) areolar tissue
(e) connects a muscle
with a bone.
Selina Concise Biology Class 7 ICSE Solutions - Plant And Animal Tissues 1

Question 6.
How do you rank the following among cells, tissues, organs, or organism ?

  1. Amoeba : organism
  2.  Euglena: organism
  3. Skin : organ
  4. Lungs : organ
  5. Neuron : tissue
  6. Cardiac muscles: Ti1ue

Question 7.
Each of the tissues listed in Column A is related to one of the functions
given in Column B. Match the lines correct pairs by drawing
Selina Concise Biology Class 7 ICSE Solutions - Plant And Animal Tissues 2

Question 8.
Name the kind of tissue that

  1.  Carries oxygen around your body — Blood tissue.
  2.  Brings about movements in animals — muscular tissue.
  3.  Transports food to different parts of plant— phloem.
  4.  Transports water in plants — xylem.
  5.  Supports an animal’s body — connective tissue (supportive)
  6.  Binds different tissues together — Fibrous connective tissue.
  7.  Conducts messages from one part of the body to another — nervous tissue.

Question 9.
Based on the following information, identify the three types of epithelial tissue in the figures given below :
Selina Concise Biology Class 7 ICSE Solutions - Plant And Animal Tissues 3

(i) Cuboidal epithelium : It consists of a single layer of cuboidal cells.

(ii) Columnar epithelium: It is composed of tall, cylindrical cells with oval nuclei usually placed at the base of the cells.

(iii) Ciliated epithelium : It consists of cells being hair-like cilia on their free surface.
Answer:
(i) fig. b (ii) fig. a (iii) fig. c

Question 10.
Write three differences between the two principal vascular tissues found in plants.
Answer:
Xylem

  1. Transports water and minerals absorbed by the roots to other plant parts.
  2. Consists mainly of dead cells.
  3. Conduction is unidirectional i.e. only upwards from the roots.

Phloem

  1. Conducts food manufactured in the leaves to other plant parts.
  2. Consists mainly of living cells.
  3. Bidirectional conduction i.e. both upwards and downwards from the leaves.

 

Selina Concise Biology Class 7 ICSE Solutions – Classification of Animals

Selina Concise Biology Class 7 ICSE Solutions – Classification of Animals

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APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 7 Biology. You can download the Selina Concise Biology ICSE Solutions for Class 7 with Free PDF download option. Selina Publishers Concise Biology for Class 7 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.

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Selina Concise ICSE Solutions for Class 7 Biology Chapter 3 Classification of Animals

Synopsis

  •  The animals can move from one place to another in search of food and shelter and this is called locomotion.
  •  The vertebrates can be classified into five classes:
    1.  Pisces (Fishes)
    2.  Amphibia (Frogs)
    3.  Reptilia (Lizards and Snakes)
    4.  Aves (Birds)
    5. (Mammalia (Milk – nourishing animals)
  • Pisces / Fishes
    1.  have streamlined body shape
    2.  Locomotion with the help of fins
    3.  Body covered with scales.
    4.  Breathe through gills.
    5. Example: Dogfish, Catla
  •  Amphibia / Frogs
    1.  can live in water as well as on land.
    2. always lay their eggs in water.
    3. body covered by a slimy and slippery skin
    4. breathe through lungs and skin.
    5. Example: Frog and toads.
  •  Reptilia
    1.  Mostly live on land
    2.  Skin is dry and scaly
    3.  Breathe through lungs
    4. Females lay eggs on land
    5. Example: Lizards, snakes, crocodiles
  • Aves / Birds
    1. Body covered with feathers.
    2. Have wings to fly.
    3. Scales only on legs.
    4. Have jaws with homy beak and have no teeth.
    5. Example: Pigeon, hen
  • Mammalia / Milk – nourishing animals.
    1. Body covered with hairs.
    2. Posses projecting external ears.
    3. Give birth to young ones.
    4. Mothers suckle their young ones.
    5. Have a tail and four limbs. (Tail may become vestigeal)
    6. Example: dog, tiger, man.
  • Invertebrates can be further divided into nine groups.
    1. Protozoans
    2. Porifera
    3. Coelenterates
    4. platyhelminths
    5. Nemathelminths
    6. Annelids
    7. Molluscs
    8. Arthropoda
    9. Echinoderms
  • Coelenterates
    1. Now called cnidarians
    2. Body is tube like with only one opening called the mouth.
    3. Mouth is surrounded by finger like processes called tentacles for catching food.
    4. Body radially symmetrical
    5. Example: Hydra, Sea-anemone, jelly fish
  • Flatworms / Platyhelminths:
    are usually found as parasites in the bodies of other animals.
    Example: Tapeworm, liver fluke.
  •  Ascaris: The round worm is found in the small intestine of especially those who eat with the unwashed hands.
  •  Annelids:
    1.  are also called segmented worms
    2.  body is composed of rings or segments
    3.  have a body cavity.
    4. have special organs of excretion called nephridia.
      Example: earthworm, leech.
  •  Arthropods can be further divided into
    1.  Crustacea : head and thorax are fused and have many jointed legs.
      Example: crab, lobsters etc.
    2.  Myriagoda: Body is divided into many segments and has one or two pairs of legs on each segment.
      Example: Centipede, millipede.
  •  Insecta: Body is divided into three regions – head, thorax and abdomen.
    — Has three pairs of legs.
    — Have two pairs of wings.
    Example: ant, housefly, butterfly.
  •  Arachnida: Head and thorax fused
    — Have four pairs of legs.
    — Have no wings.
    Example: Spider, Scorpion
  •  Echinoderms
    — also called spiny-skinned animals.
    — Body is star – like or ball – like
    — Have no head or tail.
    — Have no left or right side.
    Example: Starfish, sea urchin.
  • A species can be defined as a group of individuals having common characteristics and which come together to pro¬duce young ones.
  •  Scientific name consists of two parts. The first part is the genus name while the second part is the species name.
    This type of naming is called Binomial nomenclature.
  • The animals can be classified also on the basis of their food habits into as follows.
    (a) Herbivorous:Feed on plants e.g. cow, goat.
    (b) Carnivorous:Feed on the flesh of other animals  e.g. lion, tiger etc.
    (c) Omnivorous:Feed on both plants as well as flesh of other animals, e.g. man, bear etc.
    (d) Parasites:Live either inside or on the outside of the body of other animals and plants and take food from them.
    Example: Leech, mosquitoes etc.

Activity 3
Look at the four animals shown alongside.
Which four classes of vertebrates are represented by them ? Name these classes.
Selina Concise Biology Class 7 ICSE Solutions - Classification of Animals 1

Answer:
1. Class Mammalia
2. Class Mammalia
3. Class Reptilia
4. Class Pisces

Review Questions

MULTIPLE CHOICE QUESTIONS

1. Tick (✓) the appropriate answer:

(i) Identify the aquatic animal with scaly skin which breathe with gills –
(a) Rohu
(b) Tortoise
(c) Sparrow
(d) Rat

(ii) The unicellular organism causing malaria –
(a) Amoeba
(b) Paramecium
(c) Euglena
(d) Plasmodium

(iii) Identify the animal which is not an Arthropoda —
(a) Prawn
(b) Butterfly
(c) Earthwonn
(d) Spider

(iv) Scientist who introduced binomial nomenclature is —
(a) Charles Darwin
(b) Carolus Linnaeus
(c) Robert Hooke
(d) Gregor Mendel

Short Answer Questions
1. Give two examples of each of the following:
(i) Amphibians:
Ans. Amphibians: 1. Frog 2. Toad
(ii) Segmented worms:
Ans. Segmented worms: 1. Earthworm 2. Leech
(iii) Reptiles:
Ans. Reptiles: 1. Snake 2. Lizard
(iv) Coelenterates:
Ans. Coelenterates : 1. Hydra 2. Jellyfish
(v) Arthropods:
Ans. Arthropods: 1. Crab 2. Centipede
(vi) Flatworms:
Ans. Flatworms: 1. Tapeworm 2. Liverfluke

2. Give names of two animals which are found as parasites inside the human intestine.
Ans. (a) Tapeworm (b)Ascaris ’

3. Name one example each of an animal which shows the following characteristics:
(i) Fixed animals with a pore-bearing body:
Ans. Fixed animals with a pore-bearing body: sponge
(ii) Star-shaped body:
Ans. Star-shaped body: Star-fish
(iii) Can live in water as well as on land:
Ans. Can live in water as well as on land: Frog
(iv) Has a flattened ribbon-like body:
Ans. Has a flattened ribbon-like body: Tapeworm

4. Write one difference each between the following pairs:
(i) Porifera and Coelenterata.
(ii) Arthropoda and mollusca.
(iii) Invertebrates and Vertebrates
(iv) Platyheminthes and Nematoda
Answer:
(i) Porifera and Coelenterata.
Porifera

  1.  Body is porous i. e. bears many tiny pores to draw water into the body cavity.
  2.  e.g. Sponge

Coelenterata

  1. Sac-like body with only one opening i.e. mouth.
  2. e.g. Jelly fish, hydra,sea-anemone.

(ii) Arthropoda and mollusca.
Arthropoda 

  1.  These are animals with
  2.  They have segmented body.
  3.  They may or may not have wings
    Example: Crab.

Mollusca

  1.  Move with the help of a muscular foot.
  2.  Soft body which is not segmented.
  3.  Body enclosed in a hard shell Example: Octopus

(iii) Invertebrates and Vertebrates

Invertebrates

  1.  The animals which do not have a back bone.
  2.  They are further classified into nine groups.
    Example: Octopus, Starfish.

Vertebrates

  1.  The animals which have a back bone or a vertebral column.
  2.  They are further classified in to five groups.
    Example: Human Being, Lizard.

(iv) Platyheminthes and Nematoda
Platyheminthes

  1.  Body thin and flattened.
  2.  Mostly live as parasites in the bodies of other animals (hosts)
    e.g. Tapeworm.

Nematoda

  1. Body is rounded and unsegmented.
  2. Mostly live as parasites in the body of animals including humans.
    e.g. Roundworm commonly called Ascaris.

5. Match the animals given under column A with their respective classification group given under column B –

Column A                                          Column B
Selina Concise Biology Class 7 ICSE Solutions - Classification of Animals 2
Selina Concise Biology Class 7 ICSE Solutions - Classification of Animals 3
Answer:

Selina Concise Biology Class 7 ICSE Solutions - Classification of Animals 4
  

6. Write the characteristics of class Aves with reference to their body covering and jaws.
Answer:

The characteristics of class Aves are:

  1.  Body is covered with feathers.
  2.  They have wings to aid flying
  3.  They have scales on legs.
  4.  They have no teeth.
  5. They have jaws provided with homy beaks

7. Categorise the following animals under their appropriate columns of classification.
Selina Concise Biology Class 7 ICSE Solutions - Classification of Animals 5

Answer:
Worms – Arthropods, Butterfly, Ascaris, Scorpion, Honey bee, Liverfluke, Leech, grasshopper, Eathworm
Molluscs – Snail
Fishes – Rohu
Amphibians – Toad, Frog
Reptiles – Snake, Lizard, Turtle
Birds – Parrot, Pigeon
Mammals – Rat, Bat, Dog, Cattle, Cow, Rabbit, Monkey, Elephant