TEACHING NOTES BIOLOGY FORM FOUR

TEACHING NOTES BIOLOGY FORM FOUR

Topic 1: CLASSIFICATION OF LIVING THINGS

LEARNING OBJECTIVES

BY THE END OF THE TOPIC STUDENT SHOULD BE ABLE TO:

➢ Explain general and distinctive features of division coniferophyta.

➢ Describe the structure of pine.

➢ Explain the advantages and disadvantages of the division coniferophyta.

➢ Explain general and distinctive features of division Angiospermophyta.

➢ Outline the classes of division Angiospermophyta and their distinctive features.

➢ Describe the structure of representative plants under each class ( monocoty and dicoty).

➢ Explain the advantages and disadvantages of the division Angiospermophyta.

            DIVISION CONIFEROPHYTA

Coniferophyta is a division containing cone- bearing plants with needle shaped leaves

The smaller male cones produce a yellowish powder called pollen. It contains the male sex cells of gametes. The large female cone bears small seed like structure called ovules. This contains female gametes.

The male cone is comparable to a flower but consisting only of pollen producing structures. The pollen is formed on the leaf like scales of the cone. The female cone is comparable to a flavor but with ovule forming parts only. The ovules are attached to the leaf scales of the cone

The distinguish features and characteristics of the organism in this Division are

1. They are mostly shrubs and trees, with needle shaped leaves

2. Their reproductive structures are cones

3. The ovules are not enclosed inside an ovary wall

4. The dominant generation is the sporophyte

5. The majority are evergreen. (they keep their leaves all year round)

6. They are widely distributed. (are commonly found in areas with cold climate)

ADVANTAGES

• Conifers are relatively fast growing tress

• Are grown in plantations and produce useful timber (softwood)

• They are used extensively in the building industry, paper making and in furniture making

• The trunks of conifers grow very tall and straight. They are often used as telegram poles

DIVISION ANGIOSPERMOPHYTA

(FLOWERING PLANTS)

This division contains wide variety of forms, but all have common distinctive features as you will see

There are two classes of angiosperms

1. Monocotyledonae

2. Dicotyledonae

The feature of angiosperms is leaves, stem, roots and flowers.

Nearly all angiosperms have the same structure in their feature modified according to type and function

1. Sepal: protects the flower parts when it is in bud

2. Petals: are often brightly colored to attract insect to pollinate the flower

3. Stamen: produce the male gametes

4. Carpel: produce the female gametes

• The flower of angiosperms has male structure called stamens. These have a structure called filament support anthers which produce pollen

• The female structures are called carpels. A carpel is compared of stigma, style and ovary. The ovules are formed inside the ovary. Once a carpel has been pollinated and ovule present successfully fertilized the carpel becomes a fruit and the ovules become seeds.

The Distinguishing features of Angiosperms are
          1.Their reproductive structure are flowers

• When anthers and carpels are found in the same flower e.g. Delonix region the flower is said to be bisexual. Some plants produce uni sexual flower (maize produce) produce male flower that can release pollen and female flowers that produce ovules.

2. Ovules are enclosed in an ovary and hence the seeds are enclosed in a fruit.

3. Angiosperms vary greatly in form, size and habitat.

• They can be woody e.g. coconut tree, non- woody (maize plants) some are very small such as groundnut plants while others are very large such as baobab trees

4. They occur in wide range of terrestrial (land) and aquatic (usually fresh water) habitat

Comparing Monocots and Dicots