BIOLOGY F4 CHAPTER 2: CELL BIOLOGY AND ORGANISATION

Question 1

What are the characteristics and functions of mitochondrion?

Answer 1

Characteristics:
1. It is rod-shape and spherical
2. It consists two layers of membrane which are smooth outer membrane and folded inner membrane
3. Contains enzymes that play a role in cellular respiration

Functions:
1. A site that generates energy through the glucose oxidation process during cellular respiration
2. Energy is released in form of ATP ( Adenosine Triphosphate ) to be used by cells

Question 2

What are the characteristics and functions of centriole?

Answer 2

Characteristics:
1. Small cylindrical components that exist in pairs in animal cells
2. Made up of comples arrangement of microtubules
3. Does not exist in plant cells

Functions:
1. Forms spindle fibre during cell divison in animal cells

Question 3

What are the characteristics and functions of golgi apparatus?

Answer 3

Characteristics:
1. Consists a stack of a parallel flattened sacs that are coated by a single cell membrane
2. New membrane is added at one end of the golgi apparatus and vesicles bud off at the other end

Functions:
1. Processes, modifies, packs and transport chemicals such as protein, carbohydrate, and glycoprotein ( combination of carbohydrate and protein )

Question 4

What are the characteristics and functions of plasma membrane?

Answer 4

Characteristics:
1. Outer membrane that surrounds the entire content of cell
2. Made of protein and phospholipids
3. Thin and elastic film
4. Partially permeable

Functions:
1. Separates content of cell from the external environment
2. Controls movement of substances into and out of the cell
3. Allows exchange of nutrients, respiratory gases and waste materials between cells and their surrounding

Question 5

What are the characteristics and functions of lysosome?

Answer 5

Characteristics:
1. Small spherical sacs enclosed in a single membrane
2. Contain hydrolytic enzymes

Functions:
1. Hydrolyses complex organic molecules such as protein, nucleic, acid and lipid
2. Break down bacteria and component of damaged cells

Question 6

What are the characteristics and functions of nucleus?

Answer 6

Characteristics:
1. Largest component in the cell
2. Spherical, compressed and enclosed in nuclear membrane with many pores
3. The nucleus contains chromosomes, nucleolus, and nucleoplasm

Functions:
1. Controls all cell activities
2. Has chromosomes that contains deoxyribonucleic ( DNA ) DNA determines the cell characteristics and metabolic function

Question 7

What are the characteristics and functions of ribosome?

Answer 7

Characteristics:
1. Small, compact and spherical granules
2. Consists of protein and ribonucleic acid ( RNA )
3. Ribosome are present on the surface of the rough endoplasmic reticulum or exist freely in cytoplasm

Functions:
1. Site for protein synthesis

Question 8

What are the characteristics and functions of endoplasmic reticulum?

Answer 8

Characteristics:
1. Consists of a system of interconnected folded flattened sacs
2. Endoplasmic reticulum membrane is continuous with the nucleus membrane
3. There are two types of endoplasmic reticulum which is rough endoplasmic reticulum has ribosomes attached on the surface while smooth endoplasmic reticulum does not have ribosomes

Functions:
1. The transport system within the cell
2. Provides a wide surface for enzyme attachment and chemical reactions
3. The rough endoplasmic reticulum transport protein synthesized by ribosomes
4. the smooth endoplasmic reticulum synthesizes and transports glycerol and lipids, also carries out the detoxification of drugs and metabolic by-products

Question 9

What are the characteristics and functions of chloroplast?

Answer 9

Characteristic:
1. Oval shaped
2. Consists of 2 layers membrane
3. Contain chlorophyll pigment in the grana that gives plant a green colour

Functions:
1. Chlorophyll absorbs sunlight and converts it into chemical energy during photosynthesis

Question 10

What are the characteristics and functions of vacuole?

Answer 10

Characteristics:
1. Liquid filled-sac which is the cell sap
2. A vacuole in surrounded by tonoplast membrane
3. Young plant cell have many small vacuole while matured plant have a large vacuole
4. The vacuole in animal cells is small
5. Cell sap contains water, organic acid, sugars, amino acids, enzymes, mineral salts, oxygen, carbon dioxide and metabolic by-product

Functions;
1. Water is absorbed into the vacuole plant cell and the cell becomes turgid
2. In unicellular animals, the vacuole contracts during osmoregulation, osmosis and excretion

Question 11

What are the characteristics and functions of cytoplasm?

Answer 11

Characteristics:
1. Consists of a jelly-like medium that contains components of the suspended cells
2. Contains organic compounds such as proteins, lipids and carbohydrate also contains inorganic compound such as potassium ions

Functions:
1. Acts as a mediums for biochemical reactions in cells

Question 12

What are the characteristics and functions of cell wall?

Answer 12

Characteristics:
1. A strong and rigid outer layer
2. Made from cellulose fibre
3. Fully permeable

Functions:
1. Maintains the shape of plant cells
2. Provides mechanical support to plant cells

Question 13

What are the similarities and differences between animal cells and animal cells?

Answer 13

Similarities:
1. Both cells are made up of nucleus, cytoplasm, plasma membrane, Golgi apparatus, mitochondrion, endoplasmic reticulum and ribosomes

Differences:
1. Plant cells have a fixed shape while animal cells does not have a fixed shape
2. Plant cells have a cell wall while animal cells does not have a cell wall
3. Plant cells have chloroplast while animal cells does not have chloroplast
4. Plant cell has a large vacuole while animal cell does not or if presents it is small
5. Plant cell stores carbohydrate in the form of starch while animal cell stores carbohydrate in the form of glycogen
6. Plant cell does not have centriole while animal cell does

Question 14

What is unicellular organisms?

Answer 14

Unicellular organisms is only made up of one cell

Question 15

Explain the movement of Amoeba sp. Paramecium sp.

Answer 15

Amoeba sp.
1. Constantly changes its shape when encounters obstacles
2. moves by extending out its pseudopodium ( false feet )
3. This is followed by the flow of cytoplasm into the extended pseudopodium

Paramecium sp.
1. Moves by rhythmic cilia beats

Question 16

Explain the responding stimuli of Amoeba sp. and Paramecium sp.

Answer 16

Both respond to stimuli such as chemicals, touch and bright light by moving away from it

Question 17

Explain the respiration of unicellular organisms

Answer 17

Exchange of oxygen and carbon dioxide gases occurs through the plasma membrane by simple diffusion on the surface of the cell

Question 18

Explain how Amoeba sp. and Paramecium sp. consume their nutrition

Answer 18

1. Amoeba sp. move towards its food by extending out its pseudopodium to trap food particles by phagocytosis
2. Paramecium sp. the presence of cilium beats helps transfer food particles into oral groove
3. The food vacuole is combined with lysosome
4. The food particles are hydrolyzed by enzymes lysozyme in the lysosomes
5. The nutrients are absorbed into the cytoplasm
6. Undigested food is discharged when Amoeba sp. moves
7. Undigested food in Paramecium sp. is discharged through the anus

Question 19

Explain the growth of Amoeba sp and Paramecium sp

Answer 19

Both grow by synthesizing new cytoplasm

Question 20

Explain the excretion process of Amoeba sp and Paramecium sp.

Answer 20

1. Waste such as carbon dioxide and ammonia are removed by diffusion
2. Both live in freshwater environment, water will diffuse by osmosis and fill the contractile vacuole
3. When the vacuole expands to the maximum size, contraction occurs and water is excreted from time to time
4. This process is called osmoregulation

Question 21

Explain the reproduction of Amoeba sp and Paramecium sp

Answer 21

1. When the conditions are suitable and there is plenty of food both will reproduce via asexual reproduction that is binary fission through mitosis
2. However, when the conditions are not suitable such as dry condition, low temperature and food shortage, the Amoeba sp forms spores that will only germinate when the environment improves
3. For Paramecium, sexual reproduction, that is conjugation occurs when the environment conditions are not suitable

Question 22

What are the characteristics and functions of muscle cell?

Answer 22

1. Arranged as multinuclear striated fibre
2. Contract and relax to generate movement

Question 23

What are the characteristics and functions of nerve cell?

Answer 23

1. Long and thin in shape
2. Functions in sending nerve impulse

Question 24

What are the characteristics and functions of white blood cell?

Answer 24

1. Can change shape
2. Functions in destroying pathogens

Question 25

What are the characteristics and functions of epithelial cell?

Answer 25

1. Thin and flat cells 2. Coats the surface of organs such as the digestive tract

Question 26

What are the characteristics and functions of red blood cell

Answer 26

1. Does not contain a nucleus 2. Shaped as a biconcave disc 3. Functions to optimize the transportation of oxygen

Question 27

What are the characteristics and functions of sperm cell?

Answer 27

1. Has a long tail to enable it to swim towards the ovum in Fallopian tube 2. The head carries a set of chromosomes from the male

Question 28

What are the characteristics and functions of sieve tube element?

Answer 28

1. Long cylindrical tube arranged from end to end 2. Transport organic materials from leaves to storage organs such as fruits

Question 29

What are the characteristics and function of xylem vessel?

Answer 29

1. Long, continuous hollow cube 2. Functions in transporting water and mineral salts from the root to the other parts of the plant

Question 30

What are the characteristics and functions of palisade mesophyll cell?

Answer 30

1. Consists of long cylindrical cells, arranged vertically and close to each other 2. Contain high chlorophyll density 3. This arrangement allows maximum absorption of sunlight for photosynthesis

Question 31

What are the characteristics and functions of spongy mesophyll cell?

Answer 31

1. Cells are loosely arranged with lots of air space between 2. Large air space allows exchange of gas from the inside of the leaves to the palisade mesophyll cells

Question 32

What are the characteristics and functions of guard cell?

Answer 32

1. Modified lower epidermal cells with thicker cell wall on the inner side 2. Controls the opening and closing of the stoma. Stoma is the opening that allows the exchange between oxygen and carbon dioxide

Question 33

What are the characteristics and functions of hair root cell?

Answer 33

1. Has a long projection which adds surface area for the absorption of water and mineral salts

Question 34

What is tissue?

Answer 34

Tissues are a group of cells that have the same structure and function and are arranged together to carry out a specific function

Question 35

What are the functions of epithelial tissue?

Answer 35

1. To cover the outer surface 2. To covers the surface of the mouth and oesophagus 3. To covers the surface of lung, body cavities and blood vessels 4. To covers the surface of the trachea and bronchus 5. To lines tubules, glands and kidney duct 6. To covers the small intestine

Question 36

What are the muscle cell and each of its function?

Answer 36

1. Smooth muscle - Contraction and relaxation of smooth muscle enable involuntary actions such as peristalsis along the digestive tract 2. Skeletal muscle - Involved in controlled movement. Skeletal muscle contract and relax to generate movement in bones and limbs 3. Cardiac muscle- Builds walls of the heart that contract to pump blood to the whole body. Cardiac muscle contraction is involuntary

Question 37

What is nerve tissue?

Answer 37

1. Nerve tissue is made of neuron and nerve cells. 2. Each neuron consists of a cell body and nerve fibre called dendrite and axon

Question 38

What are connective tissues and each of its functions

Answer 38

1. Blood tissue - Blood plays a functional role in regulation, transportation and protection 2. Loose connective tissue - It links the epithelial tissue to the tissue below it, and fixes the organs in their positions 3. Bone - forms the body frame and protect the internal organs 4. Fibrous connective tissue - These tissue form tendons and ligaments. The tendon connects the bones and muscles and the ligament connects the bones to bones 5. Adipose tissue - Connective tissue keep fat under the skin dermis and the surface of all the main organs 6. Cartilage - Cartilage encloses the bone tips to prevent the bone from wearing out

Question 39

What are the ground tissues and its functions?

Answer 39

1. Parenchyma tissue - Functions to store starch, protein and water. This tissue also can carry out photosynthesis 2. Collenchyma tissue - Functions in giving support to young, non- woody stems ( herbaceous plants ) 3. Sclerenchyma tissue - Functions in giving support and mechanical strength to all mature parts of plant