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Chapter 1

The Leaf

Class 6 - Concise Biology Selina


Multiple Choice Questions

Question 1

Identify the plant which has compound leaves:

  1. Banana
  2. Banyan
  3. Mango
  4. Rose

Answer

Rose

Reason — In Rose leaf, the leaf blade or lamina is divided into smaller units called leaflets. Hence, rose leaf is a compound leaf.

Question 2

Which one of the following is not an insectivorous plant:

  1. Pitcher plant
  2. Venus flytrap
  3. Bladderwort
  4. Cactus

Answer

Cactus

Reason — Cactus has modified leaves into spines due to which it does not trap insects.

Question 3

This leaf shows parallel venation

  1. Banana
  2. Mango
  3. Banyan
  4. Guava

Answer

Banana

Reason — In Banana leaves, veins runs parallel to each other.

Question 4

The point on the stem from where the leaf arises is :

  1. Petiole
  2. Lamina
  3. Node
  4. Trunk

Answer

Node

Reason — The points on the stem from where the leaves and branches originate are called nodes.

Question 5

Which one of the following is essential for photosynthesis :

  1. Carbon dioxide
  2. Nitrogen
  3. Oxygen
  4. Soil

Answer

Carbon Dioxide

Reason — Out of the given options, Carbon dioxide is needed for photosynthesis.

Short Answer Questions

Question 1

Name the following:

  1. The part of the plant which grows under the ground.
  2. The part of the plant which grows above the soil.
  3. The wide flat portion of the leaf.

Answer

  1. Root
  2. Shoot
  3. Lamina / Leaf Blade

Question 2

What are the four functions of roots?

Answer

The main four functions of the roots are as follows:

  1. It helps to anchor the plant firmly to the soil.
  2. It absorbs water and minerals from the soil for the growth of the entire plant.
  3. It transports the absorbed water and minerals to the shoot system.
  4. It binds the soil together so that it does not get washed away during rain or blown away by wind.

Question 3

Mention the functions of the following:

  1. Spines
  2. Tendril
  3. Scale leaves

Answer

  1. Spines — Spines are modifications of leaves as a pointed structure that help to reduce the loss of water by transpiration.
  2. Tendril — Incase of certain weak-stemmed plants, leaves or leaflets are modified into wiry, coiled structures called tendrils. They coil around the object they touch and support the plant to climb up.
  3. Scale Leaves — Leaves modified as thick and fleshy or thin and dry are called Scale Leaves. Their function is to store food and protect the buds.

Question 4

Define venation. What are the different types of venation found in the leaves?

Answer

Arrangement of veins in the lamina is called venation. It is mainly of two types

  1. Reticulate Venation — In this type of venation, veins and veinlets are irregularly distributed in the lamina, forming a network. Example - Mango, Peepal, etc.
  2. Parallel Venation — In this type of venation, veins run parallel to each other. Example - Banana, Maize, etc.

Question 5

Describe the modifications of leaf in any one insectivorous plant?

Answer

In Venus Flytrap, the leaves have long pointed hairs. It is divided into two parts having midrib in between like a hinge. When an insect visits the leaf, it closes its two parts and traps the insect. The insect is then digested by digestive juices secreted by the plant.

Question 6

Write the two main functions of leaves?

Answer

Two main functions of the leaves are:

  1. Photosynthesis.
  2. Transpiration.

Question 7

Define:

  1. Photosynthesis
  2. Transpiration

Answer

Photosynthesis — Photosynthesis is the process by which a plant leaf prepares own food from water and carbon dioxide in the presence of chlorophyll and sunlight.

Transpiration — Transpiration is the process by which water is lost in the form of water vapour by evaporation from the surface of leaves and other aerial parts of a plant.

Long Answer Questions

Question 1(i)

Giving examples, differentiate between Tap root and Fibrous root

Answer

Differences between Tap Root and Fibrous Root:

Tap rootFibrous root
There is one large, thick main root.There is a cluster of root of the same thickness.
Penetrates deeply into the soil.Does not penetrate deeply, is shallow.
Tap roots are found in dicot plants.Fibrous roots are found in monocot plants.
Example — Gram, Pea.Example — Maize, Grass.

Question 1(ii)

Giving examples, differentiate between Simple leaf and Compound Leaf

Answer

Differences between Simple leaf and Compound leaf:

Simple leafCompound leaf
Lamina is undivided and is a single piece.Lamina is divided into smaller units called leaflets.
Marginal incisions, if present, do not reach upto the midrib or petiole.Incisions reach upto the midrib or petiole.
Example — Mango, Banana, Banyan, etc.Example — Rose, Neem, Clover, etc.

Question 1(iii)

Giving examples, differentiate between Parallel venation and Reticulate Venation

Answer

Differences between Parallel venation and Reticulate venation:

Parallel venationReticulate venation
Veins run parallel to each other.Veins and veinlets are irregularly distributed in the lamina forming a network.
Parallel venation is found in monocot plants.Reticulate venation is found in dicot plants.
Example — Banana, Maize.Example — Peepal, Mango.

Question 2

What is the modification seen in Bryophyllum? Explain.

Answer

Modification seen in bryophyllum are:

  1. Bryophyllum is a plant whose leaves produce adventitious buds in their margin.
  2. The adventitious buds grow into new plants when they fall off from the parent plant.

Question 3

What purpose is served by the spines borne on the leaves of cactus ?

Answer

Cactus being a desert plant needs to conserve water. So, its leaves are modified into pointed structures called as spines to reduce the loss of water by transpiration.

Question 4

Explain why leaf survival is so important to the plant ?

Answer

Leaf survival is so important to plants because:

  1. The leaf makes food for the plants by photosynthesis.
  2. The leaf gets rid of excess water from plants through transpiration.
  3. The leaf carries out the process of respiration in plants.
  4. The leaf helps in providing cooling effect to the plant through transpiration.

Question 5

Give an example of the following and draw generalized diagrams for the same:

(i) Simple leaf and compound leaf.

(ii) Parallel venation and reticulate venation.

Answer

(i) Banyan is an example of simple leaf while Rose is an example of compound leaf.

Below diagram shows simple and compound leaves:

Give an example of the following and draw generalized diagrams for the same. Simple leaf and compound leaf. Parallel venation and reticulate venation. The Leaf, Concise Biology Solutions ICSE Class 6.

(ii) Banana is an example of parallel venation while Peepal is an example of reticulate venation.

Below diagram shows reticulate and parallel venation:

Give an example of the following and draw generalized diagrams for the same. Simple leaf and compound leaf. Parallel venation and reticulate venation. The Leaf, Concise Biology Solutions ICSE Class 6.

Question 6

Enlist some of the advantages of transpiration to green plants?

Answer

The two main advantages of transpiration to green plants are as follow:

  1. Cooling effect — The water keeps on evaporating from the leaf surface during transpiration. The heat required for evaporation of water is obtained from the plant itself and thus, the plant cools itself when it is in hot environment.
  2. Transpirational pull — The roots of the plant pull up more water from the soil to make up for the water loss during transpiration. As a result, important mineral salts, which is essential for the plant growth, are also brought along with the water from the soil.

Question 7

Why do some plants have to trap insects?

Answer

Insectivorous plants trap insects because they grow in soil which is usually thin and is also low in nutrients, so insectivorous plants eat insects to fullfil their nitrogen demand.

Question 8

Explain some of the modifications of leaves found in plants?

Answer

Modifications of leaves are as follows:

  1. Leaf tendril — In case of certain weak-stemmed plants, leaves or leaflets are modified into wiry, coiled structures called tendrils. They coil around the object they touch and support the plant to climb up. E.g., Sweet Pea.
  2. Leaf spines — In some plants, leaves are modified into pointed structures called spines. Spines help to reduce water loss by transpiration. E.g., Cactus.
  3. Scale leaves — In some plants like Onion and Ginger, thick and fleshy or thin and dry scale leaves are present, respectively. Their function is to store food and protect the buds.

Question 9

What is a tendril? Explain its use to the plants?

Answer

In case of certain weak-stemmed plants, leaves or leaflets are modified into wiry, coiled structures called tendrils. They are sensitive to touch. As they touch any object, they coil around it and support the plant to climb up. E.g., Sweet pea.

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