Science Form 1 Chapter 2-Cell As a Unit of Life

8/13/2019 Science Form 1 Chapter 2-Cell As a Unit of Life

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Chapter 2: Cell as a

Unit of LifeFORM 1





•Germ (Kuman)

• A very small thing that cause infections and diseases.

•

Nucleus (Nukleus)•The control centre of a cell which contains genetic information.

•Organ (organ)

• A group of different tissues that work together to perform a specific

function.

•System (sistem)

• A group of organs that work together to perform a specific function.

•Tissue (Tisu)

• A group of similar cells that perform a specific function.

•Vacuole (Vakuol)

•The structure of a plant cell that stores water, dissolved minerals, sugar

and waste materials.



What is a cell?

A cell is the basic unit of all living things.

All living things include plants, animals and

humans are made up of cells. A cell is the smallest part in a living thing.

The cell structures can be observed by using amicroscope.



•Plant cells and animal cells differ in their shapes and functions.



•Similarities between animal cell and plant cell:

•Have a cell membrane

•Have cytoplasm

•Have a nucleus

•Differences between animal cell and plant cell:

Animal cell Plant cell

No cell wall Has a cell wall

Indefinite shape Definite shape

Usually has no vacuoleor very small vacuole

Usually has a largevacuole

No chloroplasts Has chloroplasts



•Functions of cell structures are as follows:

Cell Structure Function

Cell wall Maintains the cell in a definite shape

Cell membrane Controls the movement of materials inand out of the cell

Cytoplasm A place which chemical reactions takeplace. Store dissolved materials.

Nucleus Controls all cellular activities. Containsgenetic information.

Chloroplasts Contains chlorophyll which absorbs

light energy.Vacuole Contains cell sap made up of dissolved

substances.



2.2 Unicellular and MulticellualarOrganisms

• A unicellular organism consists of only one cell. Examples of unicellular

organisms are Amoeba, Paramecium, Euglena and yeast.

Euglena

Paramecium Amoeba

Yeast



• A multicellular organism consists of many cells. Examples of multicellular

organisms are butterfly, ant, Hydra and Spirogyra

Sparrow Rat

Hydra

Spirogyra



Microorganisms are very fine organisms. They can only beseen under a microscope. Majority of miroorganisms areunicellular. Examples include protozoa, bacteria and

viruses.

Unicellular organisms carry out all the life processes suchas movement, response, respiration, digestion, excretion,reproduction and growth.



2.3 Cell Organisation in the Human

Body

•Human being is a multicellular organism.

•There are many different types of cells in the human body.

•Different cells perform different functions.

•Some of the examples are given below.

• A group of similar cells that perform the same function is known as a

tissue.

• An organ is a group of different tissues that carry out a certain function.

•Several different organs connected to one another and perform a

particular function form a system.

•The organization of human cells is as follow:

•Cell Tissue Organ System Organism



Type of cell Function

Nerve cell Receives and transmits nerve impulses betweensensory organs (nose, skin, eyes and ears) tothe brain and all parts of the body.

Muscle cell Allows movement of different parts of the bodythrough contraction and relaxation.

Bone cell Supports and protects the organs.

Red blood cell Transports oxygen to all parts of the body.

White blood cell Protects the body from the infection of the

microorganisms such as bacteria and virus.

Reproductive cell Involves in producing young for the nextgeneration.



Various types of systems in thehuman body, their functions and

their respective organs. Digestive

Excretory

Nervous

Endocrine

Muscular

Respiratory

Blood circulatory

Reproductive Skeletal

Lymphatic



System: Digestive System•Functions: Breaks down food materials for absorption by the body.

• Associated organs: Mouth, oesophagus, stomach, small intestines, liver

and pancreas.



System: Excretory System•Functions: Removes excretory products from the body.

• Associated organs: Lungs, skin, kidneys and urinary bladder.



System: Nervous System•Functions: Coordinates activities of the body.

• Associated organs: Brain, spinal cord and nerve fibres.



System: Endocrine System•Functions: Secretes hormones to maintain activities of the body.

• Associated organs: Pituitary glands, thyroid glands, pancreas, adrenal

glands, ovaries and testes.



System: Muscular System•Functions: Controls body movement.

• Associated organs: Muscles and tendons



System: Respiratory System•Functions: Takes in oxygen and removes carbon dioxide. Oxidises food

to produce energy.

• Associated organs: Nose, trachea, lungs, diaphragm.



System: Blood circulatory System•Functions: Transports nutrients, oxygen and excretory products.

• Associated organs: Heart, veins and arteries.



System: Reproductive System•Functions: Produces offspring.

• Associated organs: Man: Testes and penis

Woman: Ovaries, uterus and vagina



System: Skeletal System•Functions: Provides support to the body, maintains the shape of the

body, protects internal organs and allows movements of the body.

• Associated organs: Bones and cartilages



System: Lymphatic System•Functions: Protects body from diseases.

• Associated organs: Lymph nodes



2.4 Humans are Complex

Organisms

•Human beings are considered complex organisms.

•Human cells are organised into tissues, organs and systems.

•Human cells are specialised.

•They perform certain specific functions only.

•With the proper organisation of cells, life processes can be carried out

effectively.



The end

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Science Form 1 Chapter 2-Cell As a Unit of Life