Plant Life : The Leaf
Section I
A. Name the following:
1. The part of plant that absorbs water and nutrients from the soil.
= Root;
2. The type of venation in which veins are irregularly branched.
= Reticulate Venation;
3. The type of plants that traps and digests insects.
= Insectivores Plants;
4. The part of a leaf that conducts water.
= Stomata;
5. The type of leaf which has undivided lamina.
= Simple Leaf;
B. Choose the correct option.
1. Which of the following has taproot system?
a. Maize. [ ]
b. Grass. [ ]
c. Mango. [✓]
d. Banana. [ ]
2. Which of these have leaf modified to store food?
a. Barberry. [ ]
b. Prickly Pear. [ ]
c. Pea. [ ]
d. Onion. [✓]
3. This is not a part of the leaf.
a. Apex. [ ]
b. Margin. [ ]
c. Node. [✓]
d. Petiole. [ ]
4. This is the part of the leaf that is modified into a pitcher-like structure, in the pitcher plant.
a. Lamina. [ ]
b. Leaf blade. [✓]
c. leaf margin. [ ]
d. Both (a) and (b) [ ]
5. Bryophyllum reproduces by the means of its
a. root. [ ]
b. stem. [ ]
c. leaves. [✓]
d. flowers. [ ]
C. Corrects the false statements by changing the underlined word/s.
1. Rose has fibrous roots.
= Tap roots;
2. The spines found on cactus stems are modified of the stem.
= Leaves;
3. The pitcher plant grows in soil deficient in calcium.
= Nitrogen;
4. When a single leaf is present at each node, the arrangement is called opposite.
= Alternate;
5. The chemical used for colour change in starch test is hydrochloric acid.
= Iodine Solution;
D. Choose the correct option to fill in the blanks.
1. Leaves release water as vapour into the atmosphere through transpiration (transpiration/evaporation).
2. The part of stem from where leaves are arise is called nodes (nodes/internodes).
3. The root system in which the primary root gives rise to the secondary roots is called taproot (fibrous root/taproot) system.
4. In a compound leaf, the lamina is divided, and the divisions reach the midrib (reach the midrib/do not reach the midrib).
5. Leaves are modified into tendrils for support (support/protection).
E. Match the items in Column A with that which is most appropriate in Column B. Rewrite the matching pairs.
=
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Column A
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Column B
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1. Venation
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a. Arrangement of
leaf. [ ]
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2. Wheat
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b. Opposite leaf
arrangement. [ ]
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3. Rose
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c. Arrangements
of veins and veinlets. [1]
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4. Pitcher Plant
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d. Parallel
venation. [2]
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5. Onion
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e. Compound leaf.
[3]
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f. Leaf
modification for trapping insects. [4]
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g. Fleshy leaf.
[5]
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F. From each group of four words, choose the odd one out, and also name the category to which the other three belong.
=
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Column 1
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Odd One Out
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Category
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1. Root, Stem, Leaf,
Flower
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Flower
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Vegetative parts
of the plant.
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2. Petiole,
Pedicel, Leaf blade, Midrib
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Pedicel
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Part of flower.
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3. Alternate,
Opposite, Reticulate, Whorled
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Reticulate
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Venation style.
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4. Fibrous Root,
Primary Root, Tertiary root, Secondary root
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Fibrous Root
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Those are the
parts of Taproot
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5. Rachis,
Leaflets, Lamina divided completely, Veins
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Veins
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Others are the
parts of a leaf system
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Section II
G. Give reasons for the following:
1. Leaves some desert plants are reduced to prickly structures.
= Leaves of some desert plants, such as prickly pear, are reduced to prickly structures, called spines, which protect the plant from grazing animals.
2. The Leaves of the pea plant are modified into tendrils.
= In some climbers, the leaves are modified into tendrils. Leaf tendrils are slender, coiled structures that are sensitive to contact. They coil around the support and help the plant to climb. Leaf tendrils of pea plant are an example.
3. Leaves of some plants are modified to digest insects.
= Some plants that grow in soils deficient in nitrogen have modified leaves to trap and digest insects. In this way, these plants can get their required nutrients.
4. Leaves contribute to water cycle.
= Leaves release water through stomata in the form of water vapour into the atmosphere by a process known as transpiration.
5. Stems are negatively geotropic.
= Stems grow in the opposite direction of gravity.
H. Explain the following terms:
1. Reticulate Venation.
= The veins and veinlets are irregularly branched forming a network. There is a midrib in the middle of the leaf which gives out secondary veins and veinlets extending towards leaf margins. For example, leaves of dicots such as mango and peepal.
2. Petiole.
= It is the stalk that attaches the leaf to the stem. It holds the leaf blade firmly. The part of the petiole that is attached to the stem is called leaf base.
3. Simple Leaf.
= A simple leaf is one in which the lamina is not divided, for example, mango leaf. However, if the lamina is divided and the division do not reach the midrib, the leaf is still called a simple leaf, for example, grape leaf.
4. Transpiration.
= Leaves also release water through stomata in the form of water vapour into the atmosphere by a process known as transpiration.
5. Leaf Spines.
= Leaves of some desert plants, such as prickly pear, are reduced to prickly structures, called spines, which protect the plant from grazing animals.
I. Differentiate between the following:
1. Root system and shoot system.
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Root System
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Shoot System
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1. Roots are the
non-green and non-photosynthetic part of a plant.
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1. Shoots are
green and photosynthetic part of a plant.
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2. They are
positively geotropic, hydrotropic but negatively phototropic.
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2. They are
negatively geotropic, hydrotropic but positively phototropic.
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3.Roots absorb
water and nutrients from the soil.
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3. Shoots prepare
food by the process of photosynthesis.
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2. Simple leaf and compound leaf.
=
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Simple Leaf
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Compound Leaf
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1. The lamina is
not divided.
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1. The lamina is
divided into smaller leaflets.
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2. If the lamina
is divided, the divisions do not reach the midrib.
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2. The divisions
reach the midrib.
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3. A bud is
present in the axil of a simple leaf.
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3. A bud is
present in the axil of a compound leaf, but it is never present in the axil
of its leaflet.
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4. Examples :
Leaves of mango and peepal.
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4. Examples :
Leaves of Neem and rose.
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3. Parallel venation and reticulate venation.
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Parallel Venation
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Reticulate
Venation
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1. The veins are
arranged in parallel rows within the leaf .
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1. The veins and
veinlets are irregularly branched forming a network. There is a midrib in the
middle of the leaf which gives out secondary veins and veinlets extending towards
leaf margins.
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2. For Example,
leaves of monocots such as grass, wheat and banana.
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2. For Example,
leaves of dicots such as mango and peepal.
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4. Alternate arrangement of leaves and opposite arrangements of leaves.
=
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Alternate
arrangements of leaves
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Opposite arrangements
of leaves
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1. In this pattern
of leaf arrangement, a single leaf is
present at each node of the stem.
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1. In this
pattern of leaf arrangement, two leaves are arranged opposite to each other
on a single node of the stem.
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2. All the leaves
are arranged in a spiral, one at each node, such that no leaf overlaps
another.
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2. Opposite
arrangements can occur in two patterns – one pair of leaves present at a node
are arranged at roughly right angles to the next pair; the pairs of the
leaves are present in the same plane with respect to the next plane.
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3. For Example :
Sheesham and Hibiscus.
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3. For Example :
Guava and Rangoon.
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5. Leaf margin and leaf midrib.
=
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Leaf Margin
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Leaf Midrib
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1. The outline of
the leaf blade is called leaf margin.
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1. A thick vein
runs centrally through the leaf blade from its base to its apex is called the
leaf midrib.
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J. Short answer questions.
1. List the parts of a typical leaf.
= A typical leaf consists of two main parts : Petiole and leaf blade.
2. State the functions of a leaf.
= Leaves prepare food for the plant by the process of photosynthesis. In the presence of sunlight and chlorophyll, the carbon dioxide and water obtained from the environment is converted into food, as glucose.
Leaves are the site for the exchange of gases during respiration and photosynthesis.
Leaves also release water through stomata in the form of water vapour into the atmosphere by a process known as transpiration.
3. What are the functions of the fleshy leaves in onion?
= Onion leaves, enclosed within dry, scary leaves, become fleshy and thick to store food materials. These leaves are arranged in concentric rings.
4. How will you identify a monocot plant based on the root system and venation pattern?
= A monocot plant has fibrous root system and parallel venation pattern.
5. What are the leaf apex, lamina and petiole of a pitcher plant modified into?
= The lamina of a pitcher plant is modified to form a pitcher-like structure.
The leaf apex forms the lid of the pitcher and the petiole is coiled to hold the pitcher is an erect position.
K. Long answer questions.
1. State the characteristics of root and shoot.
= The characteristic of root are - Roots are the non-green and non-photosynthetic part of a plant.
They are positively geotropic, i. e. , growing in the direction of gravity. They are also positively hydrotropic, i. e., growing towards water. Roots, however, are negatively phototropic, i.e., growing away from the light.
The characteristic of shoot are - The Shoot usually grows above the soil. It consists of an erect stem that bears branches, leaves, flowers, buds, and fruits. The regions on the stem where leaves, branches, and buds are attached are called nodes. Nodes are present at regular intervals. The region between two nodes are called an internode. The angle between the stem and the leaf base at the node is called the leaf axil.
2. Explain the mode of reproduction in Bryophyllum.
= Leaves of plants such as Bryophyllum, develop small buds, called adventitious buds. On their margins. These buds grow roots and fall from the leaves of the parent plant. On coming in contact with the soil, they grow into new plants.
3. Draw a labelled diagram of a leaf having reticulate venation.
=
Reticulate Venation Of A Leaf
4. Explain the different types of leaf modifications.
= In some cases, leaves get modified into distinct structures to perform special functions. These leaves do not look like normal leaves and hence are called modified leaves. Examples of modified leaves are given below:
Leaf modified for support : - In some climbers, the leaves are modified into tendrils. Leaf tendrils are slender, coiled structures that are sensitive to contact. They coil around the support and help the plant to climb. Leaf tendrils of pea plant are an example.
Leaf modification for protection : - Leaves of the barberry itself are modified into sharp thorns, while leaves of the axillary bud are normal. Thorns protect the plant from grazing animals. For example - prickly pear.
In onions, the outer leaves are modified into scaly structures to protect the inner parts.
Leaf modification for food storage : - Onion leaves, enclosed within dry. scaly leaves, become fleshy and thick to store food materials. these leaves are arranged in concentric rings.
Leaves modification for capturing insects : - Some plants that grow in soils deficient in nitrogen have modified leaves to trap and digest insects. In this way, these plants can get their required nutrients. Plants that feed on insects are called insectivorous plants. The Venus flytrap and pitcher plant are examples of insectivorous plants.
Vegetative propagation by leaves : - Multiplication of plants by their vegetative parts such as roots, stem, and leaves is called vegetative propagation.
leaves of plants such as Bryophyllum, develop small buds, called adventitious buds on their margins. These buds grow roots and fall from the leaves of the parent plant. On coming in contact with the soil, they grow into new plants.
5. Explain the different types of leaf arrangements in plants.
= Leaves are arranged on the stem of each plant such that they get optimal exposure to sunlight. This helps the plants to capture the maximum amount of sunlight. This arrangement of leaves may be alternate, opposite, or whorled.
Alternate arrangement of leaves : -
In this pattern of leaf arrangement, a single leaf is present at each node of the stem. All the leaves are arranged in a spiral one each node, such that no leaf overlaps another. this pattern is also called spiral arrangement. The leaves of Sheesham and the hibiscus plant are alternately arranged.
Opposite arrangement of leaves : -
In this pattern of leaf arrangement, two leaves are arranged opposite to each other on a single node of the stem. Opposite arrangement can occur in two patterns. In plants such as guava, one pair of leaves present at a node are arranged at roughly right angles to the next pair. In Rangoon creeper, the pairs of leaves are present in the same plane with respect to the next plane.
Whorled arrangement of leaves : -
In this pattern of leaf arrangement, more than two leaves are present at each node of the stem. The leaves are arranged in a circle and do not overlap. This pattern is seen in the leaves of Lillum.
6. Describe an activity to demonstrate photosynthesis.
= Aim : To demonstrate photosynthesis in green leaves.
Materials required : A potted plant (outdoor plant) with large green leaves, beaker, test tube, alcohol, burner, iodine solution, and a dropper.
Procedure :
1. Keep the potted plant in dark for 48 hours to destarch the leaves.
2. Now, place the potted plant in bright sunlight for at least 5 to 6 hours.
3. Pluck a leave form the plant.
4. Place the leaf in a beaker filled with water and heat it over a burner to make it soft.
5. Now, place the leaf in a test tube partially filled with methylated spirit. heat the test tube over a hot water bath for about ten minutes. The leaf will decolourize and all the chlorophyll will be removed from the leaf.
6. Remove the leaf and place it again in hot water.
7. Place the leaf on a slab. Add a few drops of iodine solution on the leaf.
Observation : The leaf turns blue-black in colour on adding iodine solution.
Conclusion : The green leaves carried out photosynthesis in the presence of light. Glucose, a product of photosynthesis, is stored in the form of starch in leaves.
