Chapter: 01. The Leaf
Check Point
Leaves with reticulate venation Peepal, Mango, Guava (Any two from the text: Peepal, Mango, Guava) Apertures on the surface of leaves for exchange of gases Plants in which leaves are modified for catching insects Solution used for testing presence of starch in leaves A. Multiple Choice Questions
The leaf is attached to the stem at The leaves of monocot plants are (b) Sessile and have parallel venation Main functions of leaf is (d) Photosynthesis, respiration and transpiration The arrangement of veins in the lamina is called Leaves are modified into tendrils in Plants use carbon dioxide in B. Assertion-Reason Type Questions
Assertion [A]: In pitcher plant, the leaves are modified into pitcher.
Reason [R]: The pitcher is used to capture insects for food. (a) Both Assertion [A] and Reason [R] are true. Assertion [A]: In xerophytic plants like Opuntia and other cactus, leaves are modified into spines.
Reason [R]: In xerophytic plants, stem is green for photosynthesis. (a) Both Assertion [A] and Reason [R] are true. Assertion [A]: The stalk of a compound leaf is called twig.
Reason [R]: The lamina in compound leaf is divided into leaflets. (d) Assertion [A] is false but Reason [R] is true. C. Fill in the blanks with suitable words.
Neem leaves are compound. Banana leaves are sessile. The green expanded and flattened part of leaf is called lamina. In Venus flytrap the lamina is divided into two parts and have toothed margins. During the process of transpiration water vapour is lost through stomata. D. State whether the following statements are true or false. If false, rewrite the correct form of statements.
Midrib in lamina is the extension of petiole. Fleshy leaves are found in Begonia. False. Fleshy leaves for storage are found in plants like Onion; Begonia leaves are involved in vegetative propagation. Scale leaves are for saving water. False. Scale leaves are primarily for protection of buds and sometimes for food storage. Spines are for saving water. Rose leaves are simple leaves. False. Rose leaves are compound leaves. Some leaves in pea form spines. False. Some leaves in pea form tendrils for support. E. Define the following.
Photosynthesis is the process by which green leaves manufacture food from carbon dioxide and water in the presence of sunlight. Transpiration is the loss of water in the form of water vapour from the surface of a leaf. Vegetative propagation is the process by which new plants grow or multiply from some vegetative parts such as root, stem, or leaves of a plant. F. Name the process.
Loss of water from the surface of lamina. Formation of new plants from the buds present on the margin of leaf. Synthesis of food from carbon dioxide and water in presence of sunlight G. Give functions of the following.
Veins and veinlets support the lamina, distribute water and minerals, and transport food prepared by the leaf to different parts of the plant. The petiole attaches the leaf blade to the stem or branch and transports water, minerals, and food. The pitcher in pitcher plant is a modified lamina used for catching and digesting insects to supplement nitrogen requirements. Spines in cactus are modified leaves that help avoid water loss by transpiration and protect the plant from grazing animals. H. Differentiate between the following.
Monocot and dicot leaf
Simple and compound leaf
Reticulate and parallel venation
I. Match the columns.
Reticulate venation - (e) Dicot leaf Leaf tendril - (f) Sweet pea Pitcher plant - (a) Insectivorous plant Maize leaf - (b) Parallel venation Chlorophyll - (d) Photosynthesis Veins and veinlets - © Movement of water J. Answer these questions.
State the function of tendrils with an example Tendrils are modified leaves or parts of leaves that help plants with weak stems to climb by coiling around supports. An example is the leaf tendril in Sweet pea or Garden pea. Name the parts of a typical leaf. The parts of a typical leaf are the petiole and the lamina (or leaf blade). The lamina further includes the midrib, veins, and veinlets. Give three main functions of leaves. The three main functions of leaves are photosynthesis (food production), transpiration (water loss), and respiration (gas exchange). Give two examples of insectivorous plants. Two examples of insectivorous plants are Pitcher plant and Venus flytrap. (Others include Bladderwort, Sundew). In what form is food synthesised in leaves and in what form is it stored? Food is synthesised in leaves in the form of glucose and is stored in the form of starch. K. Diagram-based Questions
Given below are pictures of two leaves:
(a) What does each picture represent?
The leaf on the left, with multiple leaflets attached to a common stalk, represents a compound leaf. The leaf on the right, with a single, undivided blade, represents a simple leaf.
(b) What differences do you notice between the two. The compound leaf (left) has its lamina divided into separate leaflets, whereas the simple leaf (right) has an undivided lamina. In a compound leaf, an axillary bud is present at the base of the common stalk (rachis), not at the base of individual leaflets, while in a simple leaf, an axillary bud is present at the base of the entire leaf blade.
© Give one example of each type of leaf. Example of Compound Leaf: Rose (as depicted in image), Neem, Tamarind. Example of Simple Leaf: Mango, Peepal, Guava. L. Case-based Questions
Read the given information carefully and answer the following questions:
Leaves are the main sites of photosynthesis. These need CO_2 and water as raw material. Energy is obtained from the sun as solar energy. The food is synthesised as glucose and is transported to different parts of the plant. The food is stored as starch in different plant parts.
Photosynthesis is the process by which leaves synthesize food (glucose) from carbon dioxide and water using sunlight energy. Name the end product of photosynthesis. The end product of photosynthesis (as the initial food made) is glucose. (Oxygen is also a byproduct). Name the gas used in photosynthesis. Carbon dioxide is the gas used in photosynthesis. How does carbon dioxide enter the leaves? Carbon dioxide enters the leaves through tiny pores on their surface called stomata. ThinkZone
Why are leaves called food factories of plant? Leaves are called food factories of the plant because they are the primary sites where the plant produces its own food through the process of photosynthesis. They contain chlorophyll, which captures sunlight, and they absorb carbon dioxide and water, which are the raw materials for food synthesis. What is the source of energy for synthesis of food? The source of energy for the synthesis of food (photosynthesis) is sunlight (solar energy). Why does photosynthesis occur only in green leaves? Photosynthesis occurs only in green leaves because green leaves contain chlorophyll, the specific pigment capable of trapping solar energy, which is essential for the photosynthetic process. Other parts of the plant, or leaves that are not green, generally lack sufficient chlorophyll. Pitcher plant and Venus flytrap are green plants and synthesise their food, then, why do they kill insects? Pitcher plant and Venus flytrap are indeed green plants and perform photosynthesis to make their own food (carbohydrates). However, they typically grow in nitrogen-deficient soils, such as swampy or boggy areas. To fulfill their requirement for nitrogen (which is crucial for building proteins), they have evolved to trap and digest insects, extracting the necessary nitrogen compounds from their prey. So, they kill insects to supplement their diet with nitrogen, not for energy or carbohydrates. 
Answers to textbook exercises
