The Leaf

Differences between Tap Root and Fibrous Root:

Differences between Simple leaf and Compound leaf:

Differences between Parallel venation and Reticulate venation:

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.

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.

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.

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

Below diagram shows simple and compound leaves:

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

Below diagram shows reticulate and parallel venation:

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.

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.

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.

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.

Difference between Spines and scale leaves on the basis of significance:

Difference between Vegetative and reproductive parts on the basis of parts of the plant:

Difference between Alternate and opposite phyllotaxy on the basis of number of leaves at each node :

Difference between Pine and peepal on the basis of shape of the leaf:

Difference between Reticulate and parallel venation on the basis of 2 examples:

Diagram:

(i) One important function of axillary buds is to develop into lateral shoots or branches, contributing to the plant's overall growth and structure.

(ii) The two main functions of leaves are:

1. Photosynthesis — The process by which a plant leaf prepares or synthesises food from water and carbon dioxide in the presence of chlorophyll and sunlight is called photosynthesis.
2. Transpiration — This 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. It has a cooling effect and develops a suction force to make roots absorb more water with mineral ions.

(iii) China rose and Rose.

(iv) 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.

(v) Cactus

(i)
Plant A — Pitcher Plant
Plant B — Bladderwort
Plant C — Venus Flytrap

(ii) These plants trap insects to meet their nitrogen demands.

(iii) Pitcher plant is found abundantly in Meghalaya.

(iv) In a Pitcher plant, the lamina is modified into a pitcher.

(v) The soil where these plants usually grow is deficient in nitrates.

(i) Phyllotaxy.

(ii)
Figure A shows Alternate phyllotaxy.
Figure B shows Opposite phyllotaxy.
Figure C shows Whorled phyllotaxy.

(iii)
An example of Alternate phyllotaxy — Mint
An example of Opposite phyllotaxy — Jasmine
An example of Whorled phyllotaxy — Oleander (Nerium)

(i) Diagram of simple leaf:

Example — Banyan

(ii) Diagram of compound leaf with incision upto midrib:

Example — Rose

(iii) Diagram of compound leaf with incision upto petiole:

Example — Silk Cotton

(iv) Diagram of a simple leaf with reticulate venation:

Example — Peepal

(v) Diagram of a simple leaf with parallel venation

Example — Banana

Across :
1. Bryophyllum
2. Lamina
3. Root
4. Bud

Down :
5. Midrib
6. Spine

Rose

Reason — Rose leaf is a compound leaf with incisions upto midrib.

Cactus

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

Banana

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

Node

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

Carbon Dioxide

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

Petiole

Reason — The basal part of a leaf is a stalk called petiole, which is attached to the stem at the node.

Apical bud

Reason — The tip of the shoot has buds called apical buds or terminal buds. They are responsible for the vertical growth of the stem.

Leaflets

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

Prickly poppy

Reason — Prickly poppy has simple leaves as its lamina is undivided and is a single piece.

Nerium

Reason — Nerium has whorled phyllotaxy as it has more than two leaves attached at each node, arranged in a whorl.

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

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.

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.

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.

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.

Two main functions of the leaves are:

1. Photosynthesis.
2. Transpiration.

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.

1. The Root system and the Shoot system.
2. The Tap root system and the Fibrous root system.
3. Stem, Buds, Leaves, Flowers, and Fruits.
4. Alternate, Opposite, and Whorled.
5. Reticulate venation and Parallel venation.

1. Phyllotaxy — The arrangement of leaves on a stem or its branch is called phyllotaxy. Phyllotaxy are of three types- Alternate, Opposite, and Whorled.

2. Leaf — Leaves are the flat and green parts of the shoot that grow laterally from the nodes of the stem. They perform important functions like photosynthesis and transpiration.

3. Autotrophic nutrition — All green plants have the capability to prepare their own food, and are therefore called autotrophs, and this method of nutrition is called autotrophic nutrition.

4. Leaf tendril — 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.

5. Vegetative propagation — Sometimes new plants may also be produced from other (vegetative) parts of the plant such as the roots, stems and leaves instead of seeds. This type of reproduction is called vegetative propagation.

1. Root hairs
2. Internode
3. Sessile leaves
4. Petiole
5. Chlorophyll