BIOLOGY: FORM TWO: Topic 1 - CLASSIFICATION OF LIVING THINGS

 Join Our Groups

TELEGRAM | WHATSAPP

Schemes of Work 2024

Necta Timetables 2024

English Course - Free

Kenya Notes

                                              

TOPIC 1: CLASSIFICATION OF LIVING THINGS

Kingdom Fungi

Member of the kingdom Fungi include fairly familiar organisms such as mushrooms, toadstools and bracket fungi. There are also less obvious but very important members such as mold, which grow on bread, ripe fruits and other food.

The General and Distinctive Features of the Kingdom Fungi

Explain the general and distinctive features of the kingdom Fungi

General features of kingdom fungi

1. Fungi are found in damp or wet places
2. They have eukaryotic cells with a rigid protective wall made of chiti
3. They are heterotrophs, some are saprophytic where others are parasitic
4. They store food as glycogen
5. They reproduce using spore
6. They are non-mobile

Distinctive features of kingdom fungi

1. They have chitin in their cell wall
2. They have septate

The Phyla of the Kingdom Fungi

State the phyla of the Kingdom Fungi

Phyla of the kingdom fungi

1. Ascomycota
2. Zygomycota
3. Basidiomycota

Ascomycota

Ascomycota are also called sae fungi. They produce spore in sae-like cell called asei. These spores are called ascopores. Examples of Ascomycota are bakers’ yeast, cup fungi and ring worm fungi.

Characteristics of phyla Ascomycota

1. Their cell wall is not made by chitin but cetin polysaccharide component of phosphoric acid
2. Have granulated cytoplasm
3. Store food in form of glycogen
4. Reproduce asexually by budding and sexually by means of ascospores.

Distinctive features

1. Reproduce sexually by means of ascospores

(i) Reproduce sexually by means of ascospores

The Structure of Mosses

Describe the structure of mosses

Mosses are small, soft plants called bryophytes, that are typically 1–10 cm (0.4–4 in) tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems. At certain times mosses produce spore capsules which may appear as beak-like capsules borne aloft on thin stalks.

Advantage and Disadvantages of Mosses

Outline advantage and disadvantages of Mosses

On the advantage side, it can help to hold the bonsai soilin place and prevent it from washing out of the container. Moss can increase the water retention capability of the soil by slowing evaporation.

On the disadvantage side, a thick carpet of moss can reduce the diffusion of gases into the soil and to the roots, which can result in root rotor poor drainage conditions. Moss can grow up onto the surface roots and trunk of your bonsai, and soften their bark, promoting its decay.

Division Filicinophyta (Pteridophyta)

General and Distinctive Features of the Division Filicinophyta

Explain general and distinctive features of the division Filicinophyta

This division was formerly called Pteridophyta. The division Filicinpphyta includes a group of primitive vascular plants. The adult plant body in these plants is a sporophyte. It shows differentiation into true roots, stems and leaves. The stem is mostly herbaceous. Leaves may be smaller or larger. Vascular tissues are present in all the vegetative parts of the plant body.

Characteristics of division Filicinophyta

Members of this kingdom include horsetails, ferns and mosses.

1. Reproduction involves production of spores inside special structures called sporangiawhich occur on the underside of the leaves called sporophylls. Sprangia may sometimesbe found in groups called sori.
2. The plants may be homosporous - producing only one type of spore or heterosporous -producing two different types of spores; smaller microspores and larger megaspores.
3. They are seedless vascular plants, which contain vascular tissues but do not produceseeds.

The Structure of Ferns

Describe the structure of Ferns

Ferns are intermediate in complexity between the more primitive bryophytes (mosses, liverworts, and hornworts) and the more advanced seed plants. Like bryophytes, ferns reproduce sexually by making spores rather than seeds. Most ferns produce spores on the underside or margin of their leaves. Like seed plants, ferns have stems with a vascular system for efficient transport of water and food. Ferns also have leaves, known technically as megaphylls, with a complex system of branched veins.

In general, ferns consist of the following structures:

Fronds

The frond is the "leaf" of a fern. It is divided into two main parts, the stipe (leaf stalk or petiole)and the blade (the leafy expanded portion of the frond).

Rhizomes

Rhizomes would be comparable to "stems" in the flowering plants. Fronds arise from therhizome. In some epiphytic ferns (ferns that grow on trees) and in terrestrial creeping ferns therhizome roams widely and is quite visible.

The rhizome contains the conducting tissues (xylem and phloem) and the strengthening tissues (sclerenchyma fibres). The conducting tissue, known as the vascular bundle, carries the water, minerals, and nutrients throughout the plant.

Roots

Roots are formed from the rhizomes or sometimes from the stipe. The roots usually do not divide once they grow from the rhizome. Tree fern roots grow down from the crown and help thicken and strengthen the trunk. The roots anchor the plant to the ground and absorb water and minerals.

Sporangia

The sporangia are the reproductive structures of the ferns and fern allies. They produce the dust like spores that are the "seeds" by which ferns are propagated. Several sporangia grouped together are called a sorus. Most ferns have their sporangia on the underside of the frond, arranged in an organized pattern usually associated with veins in the pinnule (leaf). Many times(but not always) the ferns provide a protective covering for the sorus called an indusium

Spores

The "seeds" of the ferns and fern allies are called spores. Normally they are formed in groups of four. Spores contain oil droplets and sometimes chlorophyll in their nucleus.

Advantages and Disadvantages of Ferns

Outline advantages and disadvantages of ferns

Advantages of ferns

1. Some ferns are edible and hence serve as a source of food.
2. They provide nutrients to the soil to improve soil fertility.
3. They cover the soil and prevent soil erosion.
4. They are used as decoration materials.

Disadvantages of ferns

1. They harbour dangerous organisms like snakes and insects.
2. Some ferns are poisonous when eaten.