1. Diagram 1 shows the structure of a cell as seen using an electron microscope.

Diagram 1

(a) On Diagram 1, name the structures labelled K,L,M and N.[4 marks]

(b) (i) Where could this cell be found?

___________________________________________________

(ii) Explain your answer in (b) (i).

________________________________________________________________________________________________________________________________________________________________________________________________________________

[2 marks](c) What is structure K made of?

__________________________________________________________[1 mark]

(d) State the function of

(i) a mitochondrion __________________________________________________________

(ii) structure N

__________________________________________________________[2 marks]

(e) (i) What is the most important constituent of structure M?

__________________________________________________________

(ii) State the function of structure M. __________________________________________________________ __________________________________________________________

[2 marks]

(f) Explain the role of L in maintaining cell turgidity.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________

[2 marks]

2. Diagram 2.1 and Diagram 2.2 show two different types of transport processes

across the plasma membrane. [10 marks]

(a) On Diagram 2.1, label the following structures:

· Phospholipid bilayer with letter X

· Pore protein with letter Y [2 marks]

(b) State two features of the phospholipid bilayer. [2 marks]

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

(c) Name each transport process across the plasma membrane as shown in

Diagram 2.1 and Diagram 2.2.(2 marks)

Process in Diagram 2.1: _________________________________________________

Process in Diagram 2.2: _________________________________________________

(d) What is the characteristic displayed by the plasma membrane in both processes?

__________________________________________________________________

[1 mark]

(e) If substance in diagram 2.2 are sodium ion. Describe how they are transported out

of the cell. [3 marks]

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3. The Diagram 3 shows the organelles involved in the production of extracellular enzymes.

Diagram 3

(a) (i) By giving an example, explain the term extracellular enzyme.______________________________________________________________________________________________________________________________________

[2 marks]

(ii) Based on the organelles shown, explain how extracellular enzymes are produced.__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

[4 marks]

(b) The Diagram 3.2 shows the action of an enzyme and its substrate.

Diagram 3.2

(i) If the substrate used is lipid, name the part labelled P, Q and R.P : _______________________________________________Q : _______________________________________________R : _______________________________________________ [3 marks]

(ii) What is the principles of enzymatic reaction shown in Diagram 3.2______________________________________________________ [1 mark]

(iii) State three characteristic of enzyme shown in Diagram 3.2 __________________________________________________________________________________________________________________________________________________________________

[3 marks]

4. The Diagram 4.1 shows the various structures of protein.

Diagram 4.1

(a) Name the structure P, Q, R and S.P : _____________________________________________________________________Q : _____________________________________________________________________R : _____________________________________________________________________S : _____________________________________________________________________

[4 marks]

(b) Explain how

(i) a dipeptide is formed.______________________________________________________________________________________________________________________________________

[1 mark](ii) structure S is formed from structure R.

______________________________________________________________________________________________________________________________________

[1 mark]

(c) Give one example of a substance for each of the protein structures of R & S.R : _____________________________________________________________________S : _____________________________________________________________________

[2 marks]

(d) (i) What is denaturation?______________________________________________________________________________________________________________________________________

[1 mark](ii) What is the result of denaturation of proteins?

___________________________________________________________________[1 mark]

(e) State the differences between essential amino acids and non-essential amino acids.

[2 marks]

5. Diagram 5.1 shows three stages of meiosis X, Y and Z in an animal cell.

X Y Z

Diagram 5.1

a) Name the stages X, Y and Z in diagram 1.1.

X:________________________________________________________________

Y:________________________________________________________________

Z:________________________________________________________________

(3 marks)

b) Explain what happens at stage Z

____________________________________________________________________

____________________________________________________________________

__________________________________________________________

(3 marks)

c) State the chromosomal behavior at the following stages:

i) Stage X: ____________________________________________________

ii) Stage Y:____________________________________________________

(2 marks)

d) Explain the role of mitosis in the cloning of banana plant.

____________________________________________________________________

____________________________________________________________________

______________________________________________________________

(3 marks)

e) Diagram 5.2 shows a cell at a certain phase. If chromosome P is not separated,

draw the diagrams of two daughter cells which will be formed in the next phase in

the spaces provided below.

Daughter cell I Daughter cell II

Diagram 5.2

P

(2 marks)

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Paper 2 Scheme Biology

Question number

Suggested answer Score

1. (a) K: cell wall L: vacuoleM: nucleus N: chloroplast

(b) (i) in plants(ii) The presence of the cell wall, chloroplasts and a

large central vacuole clearly indicates that the cell is a plant cell.

(c) Cellulose

(d) (i) Supplies the cell with energy it requires to carry out cellular activities.

(ii) Contains chlorophyll which absorb sunlight to carry out photosynthesis

(e) (i) DNA(ii) It controls and regulates all cellular activities.

(f) When water enters the cell by osmosis it fills up the vacuole causes it to expand. The vacuole and cytoplasm press the plasma membrane against the cell wall.

4m

1m1m

1m

1m

1m

1m1m

2m

Total 13m

2(a)

(b) · the polar hydrophilic heads are contact with the extra

cellular environment and intracellular environment· the non polar hydrophobic tail of both layer point

toward each other

(c) Diagram 2.1: facilitated diffusionDiagram 2.2: active transport

(d) The plasma membrane is partially permeable / semi- permeable

(e) · sodium ion approach and bind it to the carrier protein · ATP molecules spilt to ADP and P, releasing the

energy to carrier protein.· Energy from the ATP changes the shape of the

carrier protein, allowing the · sodium ion to be transported out of the cell against

2m

2m

1m1m

1m

1m1m

1m

Y

X

the concentration gradient/ from lower concentration region to higher concentration region

Max = 3 marks

Total

1m

10m

3 (a) (i) An example is amylase.Extracellular enzyme is produced in a cell, then

packed and secreted from the cell. It catalyses its reaction outside the cell.

Total = 2m

(ii) -The instruction for making the extracellular enzyme is transcribed from the deoxyribonucleic acid (DNA) to ribonucleic acid (RNA) in the nucleus.

-The RNA then leaves the nucleus through the nuclear pore and attaches itself to the ribosome located on the endoplasmic reticulum.

-When the synthesis of the enzymes is completed, it is encapsulated in a transport vesicle which fuses with the Golgi Body. -In the Golgi Body, the enzyme is further modified before being packed in a secretory vesicle. - The secretory vesicle transports the enzyme to the plasma membrane, where it fuses with it and the enzyme is released outside the cell.

(b) (i) P : Lipase Q : Fatty acid/glycerol R : Glycerol/fatty acid

(ii) Lock and key hypothesis

(iii) - enzyme has specific site/active site to bind with specific substrate - enzyme are not change or destroyed by the reaction - enzyme can be reused after enzyme catalysed Reaction.

Total

1m

1m

1m

1m

1m

1m

1m

max=4

1m1m1m

1m

1m

1m1m

13m

4 (a) P : Primary Q : Secondary R : Tertiary S : Quaternary

(b) (i) When two amino acids combine, a condensation reaction takes place producing a dipeptide with the formation of a peptide bond joining them and water is given out.

(ii) Two more structure R combine together to form one large and complex protein molecule that is structure S.

(c) R : Enzymes, hormones or antibodies. S : Haemoglobin.

(d) (i) Denaturation is a process to break down a peptide bond causing the protein structure to change. This is caused by heat, pH, ultraviolet rays.

(ii) The protein becomes inactive and cannot function.

(e) - Essential amino acids are amino acids that cannot be synthesized by the body while non essential amino acids are amino acids that can be synthesized by the

body.

- Essential amino acids can only be obtained from a healthy diet while non essential amino acids are derived from other amino acids.

Total

1m1m1m1m

1m

1m

1m1m

1m

1m

1m

1m

12m

5 a) X: Anaphase Y: Metaphase Z: Prophase

( b) Chromosome shorten. /Nuclear membrane disappears. /The spindle fibres form.

(c) i) Stage X: The chromatids move towards the opposite polesii) Stage Y: The chromosome are arranged on the

metaphase plated)- Mitosis increases the number of cells.- Mitosis maintains the genetic contents of parent cell from 1

generation to the next.- Mitosis maintains the diploid number of chromosomes in a

species. Daughter cell I Daughter cell II

e)

Diagram 5.2

Students able to draw one daughter cell with chromosome P not

separated , and the other three chromosomes being separated

become chromatid in both daughter cell.

1m

1m

1m

2m

1m

1m

1m1m

1m

2m

12m

(2 marks)

Total