Biology Paper2 form 4

7/30/2019 Biology Paper2 form 4

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Form 4

Biology Paper 21. 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?


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__________________________________________________________

(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]


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__________________________________________________________________________

__________________________________________________________________________

___________________________________________________________

(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


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By giving an example, explain the term extracellular enzyme.___________________________________________________________________

___________________________________________________________________

[2 marks]

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.


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Diagram 4.1

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

Q : _____________________________________________________________________

R : _____________________________________________________________________

S : _____________________________________________________________________

[4 marks]

(b) Explain how

a dipeptide is formed.___________________________________________________________________

___________________________________________________________________

[1 mark]

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]

What is denaturation?

___________________________________________________________________

___________________________________________________________________

[1 mark]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.


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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)


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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

(2 marks)

Paper 2 Scheme Biology

Question

number

Suggested answer Score

1. (a) K: cell wall L: vacuole

M: nucleus N: chloroplast

(b) (i) in plants

(ii) The presence of the cell wall, chloroplasts and a

large central vacuole clearly indicates that thecell 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.

4m

1m

1m

1m

1m

1m

1m1m

P


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(f) When water enters the cell by osmosis it fills upthe vacuole causes it to expand. The vacuole and

cytoplasm press the plasma membrane against the

cell wall.

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 diffusion

Diagram 2.2: active transport

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

2m

2m

1m

1m

Y

X


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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 thecarrier protein, allowing the

sodium ion to be transported out of the cell against

the concentration gradient/ from lower concentrationregion to higher concentration region

Max = 3 marks

Total

1m

1m

1m

1m

1m

10m


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3 (a) (i) An example is amylase.

Extracellular enzyme is produced in a cell, then

packed and secreted from the cell. It catalyses itsreaction outside the cell.

Total = 2m

(ii) -The instruction for making the extracellularenzyme is transcribed from the deoxyribonucleic

acid (DNA) to ribonucleic acid (RNA) in thenucleus.

-The RNA then leaves the nucleus through the

nuclear pore and attaches itself to the ribosomelocated on the endoplasmic reticulum.

-When the synthesis of the enzymes is completed,

it is encapsulated in a transport vesicle which fuseswith 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/glycerolR : 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

1m

1m

1m

1m

1m

1m

1m

13m

4 (a) P : Primary

Q : Secondary

R : TertiaryS : Quaternary

1m

1m

1m

1m


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(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 isgiven out.

(ii) Two more structure R combine together to formone 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 peptidebond 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 besynthesized 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

1m

1m

1m

1m

1m

1m

1m

1m

12m

5 a)X: Anaphase

Y: Metaphase

Z: Prophase

(

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

(

1m

1m

1m

2m


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c) i) Stage X: The chromatids move towards the oppositepoles

ii) Stage Y: The chromosome are arranged on the metaphase plate

d)

- 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.

(2 marks)

Total

1m

1m

1m

1m

1m

2m

12m

Biology Paper2 form 4

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