Answer key

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Last edited 25 days ago by Learn LoopHQ.

Chapter: 02. The Flower

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Answer Key

Section A: Multiple Choice Questions (5 Marks)

(b) Sepal

(b) It becomes a fruit.

Section B: Fill in the Blanks (5 Marks)

pedicel

bisexual (or hermaphrodite)

fertilisation

seed coat

hypogeal

Section C: True or False (4 Marks)

False (The plumule grows into the shoot system, while the radicle grows into the root system.)

False (Some wind-pollinated flowers also produce nectar to attract other agents, or simply do not need it. The statement is too absolute.)

True

False (Seeds dispersed by wind are usually small and light and may have hair tufts or wings.)

Section D: Short Answer Questions (12 Marks)

Sessile flowers are flowers that do not have a stalk (pedicel) and are directly attached to the stem or branch.

Sepals and petals are considered “accessory whorls” because they do not directly take part in reproduction (fertilisation and seed formation). Their main role is to protect the inner whorls and help in pollination.

Two functions of a flower besides reproduction are: (1) providing ornamental value, as they are used for decoration and fragrance, and (2) serving as a source of food, as their ovaries develop into fruits and ovules into seeds, which are consumed by humans and animals.

Two characteristics of insect-pollinated flowers are that they often have bright colours and sweet smells to attract insects. They also produce nectar and have sticky pollen grains and stigmas.

During fertilisation, the pollen tube grows from the stigma down through the style to reach the ovule inside the ovary. Its role is to carry the male gametes directly to the egg cell within the ovule, facilitating their fusion.

The main advantages of seed dispersal are that it ensures the wide distribution of seeds, helps prevent overcrowding around the parent plant, and reduces competition for resources like food, space, and light, thus ensuring the survival of many seedlings.

Section E: Diagram-Based Question (4 Marks)

The process shown in the diagram is Fertilisation.

Labelled parts:

1: Stigma (or Pollen grain on Stigma)

2: Pollen tube

After the process shown is complete, part 3 (the Ovary) will develop and mature into a fruit.

Section F: Identifying and Differentiating Concepts (6 Marks)

Differentiation between Self-pollination and Cross-pollination:

Self-pollination is the transfer of pollen grains from the anther to the stigma within the same flower or between two flowers on the same plant. Pollinating agents are typically not needed.

Cross-pollination is the transfer of pollen grains from a flower on one plant to a flower on a different plant of the same species. It usually requires external pollinating agents like wind, water, insects, or animals.

Differentiation between Dicotyledonous and Monocotyledonous seeds:

Dicotyledonous seeds have two cotyledons, which are often fleshy and store food. The endosperm is typically absent.

Monocotyledonous seeds have only one cotyledon, which is usually papery, and food is primarily stored in the endosperm.

Section G: Long Answer Questions (4 Marks)

After fertilisation, significant transformations occur in the flower. The ovary swells and ripens, developing into the fruit, which serves to protect the developing seeds. Inside the ovary, the ovules undergo development and turn into seeds, each containing a new embryo. Concurrently, most other parts of the flower, such as the sepals, petals, stamens, style, and stigma, generally wither and fall off as their functions are completed.

Section H: Environmental Awareness (2 Marks)

It is important for some flowers to produce nectar because nectar serves as a food source for pollinators like bees, moths, and butterflies. By providing nectar, flowers attract these animals, which then help in transferring pollen grains from one flower to another, ensuring the process of cross-pollination essential for the plant’s reproduction and genetic diversity.

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