4.4 Plant organs: flowers

Fertilisation is the union of the special nuclear contents (gametes) of a grain of pollen and an ovule.

The nuclear content comprises a special molecule that has a code or “plan” of what the new plant must be like. We refer to this as the chromatin network, which consists of the molecule known as DNA. You will learn about the exact significance of this later.

A zygote, the beginning of the new organism, or plant, develops as soon as the nuclear content or gametes have fused.

The process of fertilisation is represented in the following sketch:

Assignment 1:

1. Present the five-step process that takes place from the moment of pollination to fertilisation:

2. Explain what happens to the following structures once fertilisation occurs:

a) ovary

b) ovule

Assessment: Mechanism of pollination and fertilisation

Were you able to analyse the mechanism and present its steps?

[LO 2.1; LO 2.2]

The formation of seeds is necessary for the process of propagation. The process of distributing the seeds or fruit ranks with this in importance.

Optional / For Enrichment:

The educator could suggest a project dealing with fertilisation through which you could investigate the interesting ways and mechanisms of propagation that form part of this process.

The David Attenborough video, The Secret life of Plants, could be viewed as an alternative. It contains astonishing visual material.

Assessment

LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

• plans investigations;
• conducts investigations and collects data;
• evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

• recalls meaningful information;
• categorises information;
• interprets information;

2.4 applies knowledge.

Memorandum

PLANT ORGANS: FLOWERS

Activity 1

Assignment 1

• Flowering plants (Angiosperms) are the most prolific and successful group of plants on the earth. Their secret is partly related to the way in which they are propagated. The key to this secret lies in the structure of the flowers and in how they operate. The fact that propagation is SEXUAL , facilitates their success.
• The flower is a structure that contains both the male and female structures of the plant. It is true that these aspects sometimes occur in separate flowers, but they generally occur together in a single bisexual (gynandrous) flower. If not, they will be unisexual, which means that there will be male and female flowers.

1. Make a drawing of the flower, showing all its parts

2. Name the functions of each of the following: