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Biology Form 1

 

Sample Notes - Full Notes in Gold Account

 

Introduction to Biology

What is Biology

Branches of Biology

Importance of Biology

Characteristics of Living Things

Comparison Between Plants and Animals

 

Introduction to Biology

 

What is Biology

 

In the primary school level you learnt about animals, plants and environment in the Science course. In the secondary level, you will continue to learn more about the animals, plants and the environment in different subjects.

 

These subjects are Agriculture, Biology, Chemistry and Physics. In Biology, you will learn more about living things and their environment in greater detail. Biology is a word that is derived from two Greek words bios and logos. Bios means life while logos means knowledge.

 

Biology is the branch of science that deals with the study of living things. The aim of biology is to explain the living world in terms of scientific principles. Living things interact with non-living things in their physical environment, hence the study of biology has been expanded to include the study of non-living things. Also included in the study is the role human beings play in shaping their environment.

 

Branches of Biology

 

Biology is a large body of knowledge that is divided into two main branches namely: botany and zoology. Botany is the study of plants while zoology is the study of animals. These branches of biology are still wide and complex. Therefore, at more advanced and specialised levels, there are smaller branches of biology that exist.

 

Examples are:

 

Ecology - the study of living things in their surrounding,

Genetics - the study of inheritance and variation,

Entomology - the study of insects, parasitology - the study of parasites.

 

The list is long. As one becomes more interested and specialised in the study of biology, he/she becomes a biologist.

 

Study Question 1

 

Name at least six other smaller branches of biology.

 
Importance of Biology

 

In studying biology, one acquires very useful knowledge that can be used in many ways. Some of these are listed below:

 

(a) In solving environmental problems such as shortage of food, poor health services, pollution, misuse of environmental resources e.g. forests, wildlife, water and soil.

 

(b) Entry into careers such as medicine, agriculture, public health, veterinary practice, animal husbandry, horticulture and dentistry.

 

(c) The scientific skills that one develops while studying biology such as observing, identifying, recording, classifying, measuring, analysing and evaluating are all very useful in every day life.

 

(d) The biological knowledge acquired is useful in international cooperation in such cases as:

  Joint development of HIV/AIDS vaccine by Kenyan and British scientists.

 

The co-ordinated fight against Severe Acute Respiratory Syndrome (SARS) involving scientists all over the world. The fight to save the ozone layer from depletion through various international agreements such as the Kyoto Protocol.  Management of resources through international treaties such as the CITES (Convention against International Trade in Endangered Species).

 

Study Question 2

 

List five professional occupations that require the study of biology.

 
Characteristics of Living Things

 

3. Repeat these procedures using the piece of stone.

4. From your observations, list as many activities as possible which the animal did.

 

Compare these activities with those of the stone. Some of the activities you have observed on the animal are some of the characteristics of living things.

 

These were; movement, feeding, response and gaseous exchange. You may also have observed excretion.

 

The remaining characteristics which you could not observe are respiration, reproduction, growth and development. These are the major characteristics of living things which are summarised below:

 

(a) Nutrition

 

Nutrition is a process by which living things acquire and utilize nutrients. Plants synthesise their own food using light energy, carbon dioxide, (carbon (IV) oxide), water and mineral salts, while animals

 

Practical Activity

 

To observe living and non-living things

 

Requirements: A small animal such as grasshopper in a jar or a rat in a cage, appropriate feed for the animal, a piece of stone and a piece of stick or a ruler.

 

Procedure

 

1.    Place the food near the animal and observe it.

2.    Disturb the animal using a piece of stick or ruler.

 

CAUTION: Do not hurt the animal, observe the animal for five minutes feed on already manufactured foods.

 

(b)  Respiration

 

Respiration is the energy producing process that occurs in all cells of living things. In this process, organic compounds are broken down to produce energy. During respiration, oxygen is usually used while energy, carbon (IV) oxide and water are the products.

 

(c)  Gaseous exchange

 

When living things take in air rich in oxygen and give out air rich in carbon (IV) oxide across a respiratory surface, then the process is called gaseous exchange.

 

(d)  Excretion

 

Excretion is the process by which waste or harmful materials, resulting from chemical reactions within cells of living things, are eliminated. Some of these materials if left to accumulate in the cells, they would cause poisoning of the living things.

 

(e)  Growth and Development

 

Growth is an irreversible increase in size and mass. On the other hand, development refers to the irreversible change in the complexity of the structure of living things. Living things grow in order to attain the maximum size and mass which are essential for their body function.

 

(f)  Reproduction

 

Reproduction is the process by which living things give rise to new individuals of the same kind. Only living things have the ability to give rise to new' individuals of their own kind.

 

(g)  Irritability

 

This is the ability of living things to perceive changes in their surroundings and respond to them

appropriately. For instance, living things react to changes in temperature, humidity, light, pressure and to presence or absence of certain chemicals.

 

(h) Movement

 

Movement is a change in position by either a part of or the whole living thing. Progressive change in position by the whole living thing is called locomotion. Movement in animals include swimming, walking, running, flying, while in some plants, it is closing of leaves, Folding of leaves, closing of flowers and growing of shoots towards light.

 

Study Questions

 

1. List the uses of the energy obtained from the process of respiration.

2. List three characteristics of living things.

 

Collection of Specimens

 

In the study of living things, you need to make collection of specimens for proper study in the laboratory. Therefore, knowledge of the apparatus used and precautionary measures to take while doing so, become necessary. Some apparatus used in collection and observation of specimens are shown in figures below.

 

A sweep net is used for catching flying insects

 

(a) A sweep net (b) Fish net

 

 

Used for trapping small fish and other small water animals.

 

Tube for applying suction mosquito netting to prevent dirt from entering suction tube

 

 

(c) Pooter (d) Bait trap

 

 Tube for collecting insects

 

For sucking small animals from rock surfaces or barks of trees.

 

Bait: Bait in a container: For attracting and trapping small animals including rats.

 

(e) Pitfall trap  (f) Pair of forceps 

 

Dustbin cover to prevent rain from getting in. For catching crawling animals.

 

For picking up small crawling animals (e.g. stinging insects).

 

 

(g) Specimen bottle (h) The Magnifying Lens 

 

  

For keeping collected specimen. Larger specimens require large bottles.

 

 One of the common apparatus that is used in biology is the hand lens. The hand lens is made up of a convex lens mounted onto a frame and has a handle. It is used as a magnifier. The magnifying power of the lens is usually marked on the frame of the lens itself, such as X8 or X10. This magnification is the indication of how much larger the image will be compared with the object.

 

Precautions during collection and observation of specimens

 

Collect only the number of specimen you need.

Do not harm specimens during the capture/collection exercise.

Do not destroy the natural habitat of the specimens. After use, return any live specimens back to their habitat whenever possible.

Dangerous/injurious specimens should be handled with care. Such include stinging plants or insects. Make use of forceps and hand gloves in such cases.

 

For highly mobile animals, the teacher will assist you to immobilise them.

 

Activity 2: Collection of specimens

 

Requirements: Sweep net, pooter, bait trap, a pair of forceps, specimen bottle, hand lens and any other appropriate apparatus.

 
Procedure

 

1. Collect a wide variety of plant and animal specimens, e.g. grasshopper, earthworm, grass, pinus leaves.

2. Place them into the appropriate containers and carry them into the laboratory.

3. Observe the specimens collected and record common features observed in:-

 

(a) animals    

(b) plants.

 

Note: Small organisms should be observed using a hand lens.

 

4. Preserve your collection.

 

Practical Activity 3

 

To collect and observe external features of plants and animals

 

Requirements: Jembe, sweep net, specimen bottle, forceps and potted plant.

 

Procedure

 

1.    Identify a mature small plant and dig it out.

2.    Using the sweep net provided, collect a grasshopper, put it in a specimen bottle and cover the bottle.

3.    Observe the external features of the two specimens. Record your observations for each specimen.

4.    Gently disturb the animal specimen and the potted plant with a blunt piece of stick or a ruler.

       Record your observation.

5.    From your observations, record the major differences between plants and animals in a table as shown in table 1.1.

 

Table 1.1: Characteristics of Living Things

 

 

 

Characteristic

 

 
 

(i) Movement

 

 
 

(ii) Colour

 

 
 

(iii) Irritability

 

 

 

The observations you have recorded, give several differences between plants and animals

Compare your list with the summary shown m table 1.2.

 

Comparison between plants and animals

 

Table: Comparison between plants and animals

 

 

Plants

 

Animals

 

(a) Most are green in colour (have chlorophyll) hence are able to make their own food from simple raw materials in presence of sunlight.

 

 

They lack chlorophyll hence feed on ready made food.

 

(b) Their cells have cellulose cell walls.

 

Their cells lack cellulose cell walls.

 

 

(c) They respond slowly to changes in their environment.

 

They respond quickly.

 

(d) Plants do not move about.

 

Most animals move about in search of food and shelter.

 

 

(e) They lacked specialised excretory organs.

 

 

Have complex excretory organ.

 

Revision Questions

 

1.(a) What is meant by the term Biology

 

   (b) List two branches of biology and for each, give a definition

 

2. State four reasons why biology should be studied.

 

3. List four differences between a plant and an animal.

 

4. A motor vehicle is able to move and break down fuel to carbon (IV) oxide (carbon dioxide) and water, yet it is not classified as a living thing. List other characteristics of living things that are not shown by a motor vehicle.

 

 

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