What are thorns?
Thorns are modified stems or branches that are sharp and protect the plant from herbivores.
[VI] Answer briefly.
Differentiate bisexual flower from unisexual flower?
Bisexual Flower: A flower that has both male (androecium) and female (gynoecium) reproductive organs. Example: Hibiscus.
Unisexual Flower: A flower that has either male reproductive organs or female reproductive organs, but not both. Example: Pumpkin.
What is cross pollination
Cross pollination is the transfer of pollen grains from the anther of a flower of one plant to the stigma of a flower of another plant of the same species. This process often involves external agents such as wind, water, insects, or animals.
Write notes on phyllode.
In some plants, such as Acacia, the petiole or leaf stalk expands and takes on the functions of the leaf. This modified petiole is called a phyllode. Phyllodes are typically flat and leaf-like, allowing the plant to carry out photosynthesis efficiently. They often develop in response to environmental conditions, such as reduced water availability, as they have a lower surface area than true leaves, which helps to reduce water loss through transpiration.
[VII] Answer in detail.
Write a brief account on pollination.
Pollination is the process by which pollen grains are transferred from the male part of a flower (the anther) to the female part of a flower (the stigma). This is a crucial step in the sexual reproduction of flowering plants, leading to the production of seeds and fruit. There are two main types of pollination:
Self-Pollination: This occurs when pollen from the anther is transferred to the stigma of the same flower or another flower on the same plant. It does not introduce genetic variation, as the offspring are genetically similar to the parent plant. Examples include beans and tomatoes.
Cross-Pollination: This occurs when pollen is transferred from the anther of one flower to the stigma of another flower on a different plant of the same species. Cross-pollination increases genetic diversity, which can result in plants that are more adaptable to changing environments. Examples include apples, plums, and pumpkins.
Explain the underground stems.
Underground Stems: These are modified plant stems that grow below the soil surface. They serve various functions, including food storage, vegetative reproduction, and survival through unfavorable conditions. There are several types of underground stems:
Rhizome: A horizontal, often thickened stem that grows underground. It has nodes and internodes, and scale leaves at the nodes. Rhizomes store food and have buds that can grow into new shoots. Examples include ginger and turmeric.
Corm: A short, vertical, swollen underground stem that stores food. It is round and flattened, with scale leaves and buds. New plants can arise from these buds. Examples include taro and gladiolus.
Tuber: An enlarged, typically spherical underground stem that stores nutrients. It has buds, known as “eyes,” which can sprout and form new plants. The potato is a well-known example of a tuber.
Bulb: A condensed stem surrounded by fleshy leaves or leaf bases that store food. The bulb has a basal plate at the bottom from which roots grow.
[IX] Consider the following statements and choose the correct one.
- Assertion: Pollination and fertilization in flowers produce fruits and seeds.
- Reason: After fertilization the ovary becomes fruit and ovule becomes seed.
Both the assertion and the reason are correct. Pollination and fertilization indeed lead to the production of fruits and seeds, and after fertilization, the ovary becomes the fruit and the ovule becomes the seed.
- Assertion: An example for conical root is carrot.
- Reason: It is an adventitious root modification.
- Assertion is incorrect, Reasoning is correct.
- Assertion is incorrect, Reasoning is incorrect.
- Assertion is correct, Reasoning is correct.
- Assertion is correct, Reasoning is incorrect.
The assertion is correct as carrot is an example of a conical root. However, the reason is incorrect because a conical root (such as a carrot) is not an adventitious root modification; it is a modified taproot. Adventitious roots are those that grow from parts of the plant other than the primary root, such as stems or leaves.
