09 June Hol Tys Sci

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Unit 10.2 MCQ

09 Jun hol TYS Homework UNIT 10.2 ALL MCQ; STRUCT QN 1-4 UNIT 12 ALL MCQ; STRUCT QN 1-6; ESSAY 2, 3

1.  D

8.  C

2.  D

9.  D

3.  B

10. C

4.  C

11.  C

5.  C 6.  B 7.  A

Unit 10.2 Struc Qn 1

Unit 10.2 Struc Qn 2

a)  August 29

a)  Female reproductive system

b)  (i) Aug 14

b)  (i) Uterus

(ii) Days 11-17 c)  Male gamete has a tail and is able to move while female gamete cannot move on its own; Male gamete has little cytoplasm but female gamete has abundant cytoplasm;

Unit 10.2 Struc Qn 3 Part

(ii) Oviduct

(iii) Ovary

c)  (i) C

(ii) Fertilisation takes place in B, oviduct; Sperms are deposited in the vagina and they swim up the uterus to oviduct. Egg release from ovary is swept down the oviduct towards uterus. A nucleus of the sperm fuses with the nucleus of the egg and fertilisation occurs; (iii) A

Unit 10.2 Struc Qn 3

Function

Ovary

Produces eggs

Vagina

Receive sperm

Oviduct

Transports eggs

Uterus

Allow embryo implantation

b) One sperm fuses with the egg. The head of the sperm enters the egg while the tail is left behind; The two nuclei fuse to form a zygote; c) Membrane of the fertilised egg, changes to prevent other sperms from entering. Fertilised egg, zygote divides to form a hollow ball of cells called the embryo; When the embryo reaches the uterus, it implants itself into the uterine lining;

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Unit 10.2 Struc Qn 4

Unit 10.2 Struc Qn 4

a) Oviduct – To transport the egg from the ovary to the uterus and it is the site of fertilization; Ovary – produce eggs and the female hormones oestrogen (developing follicles) and progesterone (corpus luteum);

b) During menstruation, the lining of the uterus breaks down and the debris and blood are discharged through the vagina (1/2) After menstruation, the uterine lining is repaired and becomes thick and spongy with blood vessels. This is brought about by the hormone oestrogen; After ovulation, progesterone maintains and thickens the uterine lining to prepare for implantation of the embryo; However, If the egg is not fertilised, progesterone and oestrogen productions stops when the corpus luteum disintegrates, uterine lining breaks down repeating the cycle (1/2)

Unit 10.2 Struc Qn 4 (not in syllabus) (c)  (i) Oviducts

(ii) Advantage – Most effective method of birth control; Disadvantage – if the woman wishes to conceive, the procedure may not be reversible;

Unit 12 MCQ 1.  C

8.  D

2.  C

9.  A

3.  B

10. B

4.  A 5.  B 6.  D 7.  A

Unit 12 Struc Qn 1 a) 

Unit 12 Struct Qn 2

(i) Alleles are different/alternative forms of the same gene found on the same loci of homologous chromosomes. (ii) A dominant allele expresses itself in the phenotype in both the homozygous and heterozygous forms. (The allele that shows its effect (in the phenotype) if at least one is present.)

b)  (i)

Parents’ Phenotype

Black X Black

Parents’ Genotype

Bb

Gametes

B

Offspring Genotypes

BB

b Bb

X

  A) Discontinuous: Eye Colour, Hair Colour  

Continuous: Height, Weight, Width of Hand

  B) Eye Colour/Hair Colour

Bb B

b Bb

bb

Offspring Phenotypes Black Black Black brown Ratio 3 Black: 1Brown

(ii) bb; bb

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Unit 12 Struc Qn 3 a)  (i) A – Ff

B – Ff

Unit 12 Structured Qn 4

C – ff

(ii) 25%

Parents’ Phenotypes Parents’ Genotypes

Normal x Normal Ff x Ff

Gametes

F

Offspring Genotypes Offspring Phenotype

FF N

f

F Ff N

f

Ff ff N A

Ratio 3 normal : 1 affected b) Sex in humans is determined by a pair of sex chromosomes, 23rd pair; Males have a X and a Y chromosome, while females have two X chromosomes;

Ai) The gene is a small segment of DNA, a hereditary factor borne on a particular locus in a chromosome that controls a particular characteristic by coding for a protein. A mutation is a sudden change in a gene, chromosome structure, or chromosome number; ii) Chemicals such as Formaldehyde; Radiation such as UV rays;

Unit 12 Structured Qn 4 Bi) The aphids become resistant to the insecticide. Hence, the insecticide will have no effect on them; ii) Biological control- Look for a natural predator of aphids;

Unit 12 Struc Qn 5 a) The gene is a small segment of DNA, a hereditary factor borne on a particular locus in a chromosome that controls a particular characteristic by coding for a protein. a)  There are two X chromosomes in the 23rd pair, which women have but not men. b)  There will be one extra chromosome in the 21st

pair/ 3 copies of chromosome 21.

Unit 5 Structured Qn 6 Ai) Alleles are alternative/different form of the same gene; They occupy the same locus, relative position, in a pair of homologous chromosomes; ii) A mutation is a sudden change in a gene, chromosome structure, or chromosome number; Mutations are inheritable and they produce variations in the population;

Unit 12 Structured Qn 6b MALE RAT

  Parents’ Phenotype   Parents’ Genotypes   Gametes   Offspring Genotype   Offspring Phenotype   Ratio

resistant Rr R r

FEMALE RAT

resistant x Rr R r

RR Rr Rr rr Res Res Res Non-Res 3 Resistant : 1 Non-Resistant

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Unit 5 Structured Qn 6

Unit 12 Essay Qn 2

c) Rats that are not resistant to Warfarin are killed by the poison. Hence, their numbers decline; Rats that are resistant to Warfarin survive and reproduce; passing the Warfarin resistant alleles to the offspring; Hence, over the years, the proportion of rats resistant to the poison increases;

Unit 12 Essay Qn 2

a)  Chromosome – highly coiled and condensed

structures that comprise of deoxyribonucleic acid double helix tightly wound around histones; Gene – The gene is a small segment of DNA, a hereditary factor borne on a particular locus in a chromosome that controls a particular characteristic. Allele – alternative form of the same gene found on the same loci of homologous chromosomes;

Unit 12 Essay Qn 3

b)  The pure bred leopard will have homozygous

dominant, SS genotype while the panther will have homozygous recessive, ss genotype. Thus all offspring will be heterozygous Ss genotype and hence have the phenotype, leopard. Let S represent allele for leopard and s represent allele for panther. F1 Phenotype

Leopard

F1 Genotype

Ss

Gametes F2 genotype F2 Phenotype

a)  Complete dominance occurs when a dominant trait

is seen phenotypically in both homozygous (XX) and heterozygous (Xx) genotypes. The recessive phenotype is only seen in homozygous recessive (xx) genotype. No intermediate phenotype exists.

x leopard x

Ss

S

s

S

s

SS

Ss

Ss

ss

Leopard Leopard Leopard panther

Ratio

3 Leopard :1 Panther

Unit 12 Essay Qn 3 Parents’ Phenotype

Night Blindness x Normal vision

Parents’ Genotype Gametes

Nn

x

N

n

F1 genotype

Nn

Nn

Phenotype

Has night blindness

Ratio

nn n

n

nn nn Normal vision

1 Night Blind :1 Normal

As ratio of children born with night blindness to those with normal vision is 1:1, there is a 50% chance that the female child will show symptoms of night blindness.

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