chapter 5: genetics

Question 1

Human chromosomes consist of

Answer 1

• 22 pair autosomes
• 1 pair of sex chromosomes (X chromosome and Y chromosome)

Question 2

What is mitosis

Answer 2

is a cell division process that forms 2 identical daughter cells, each having the same number of chromosomes and genetic content as parent cell
- mitosis takes place in somatic cells of human and animal bodies / meristematic tissue such as the tip of the roots and the shoot of the plant

Question 3

What is meiosis

Answer 3

a process where the cell divides into 4 distinct cells, each containing half the number of chromosomes in the parent cell.
- takes place in the reproductive organ to produce gametes for sexual reproduction
- takes place in male’s testes and female’s ovary
- in plant, in anther and ovary

Question 4

Process of mitosis

Answer 4

1) prophase
- chromosomes shorten and thicken and become visible
- each chromosome consists of 2 chromatids bound to the centromere

2) metaphase
- chromosomes are arranged in equatorial
- spindle fibres are fully formed

3) anaphase
- the centromere divides into 2

4) telophase
- chromatids reach the opposite poles
- nuclear membrane and nucleolus are formed again

Question 5

Process of meiosis

Answer 5

1) Prophase I
- chromosome shorten and thicken, and become visible
2) Metaphase I
3) Anaphase I
4) Telophase I
5) Prophase II
6) Metaphase II
7) Anaphase II
8) Telophase II

Question 6

Similarities between mitosis and meiosis

Answer 6

1) DNA replication
2) cell divisiond

Question 7

Differences between mitosis and meiosis

Answer 7

Mitosis
1) takes place in somatic cell
2) produce 2 daughter cells
3) NO crossing over
4) daughter cell identical to their parent cells
5) NO variation
6) number of chromosomes of daughter cells is same with parents cell

Meiosis
1) take place in reproductive cell
2) produce 4 daughter cells
3) crossing over occurs
4) daughter cells not identical to their parent cells
5) has variation
6) the number of chromosomes of the daughter cell is half the parent cell

Question 8

Importance of mitosis and meiosis

Answer 8

mitosis: growth of organisms / replace damaged or dead cells when we injured / asexual reproduction of organisms such as amoeba sp
meiosis: production of gametes

Question 9

list out dominant trait

Answer 9

1) can roll tongue
2) free earlobe
3) have dimples
4) black hair

Question 10

list out recessive trait

Answer 10

1) cant roll tongue
2) attached earlobe
3) doesnt have dimples
4) blonde hair

Question 11

Type of mutations and list out

Answer 11

1) CHROMOSOME MUTATION
- down syndrome
- turner syndrome
- klinefelter syndrome

2) GENE MUTATION
- colour blindness
- sickle cell anaemia
- thalassemia
- haemophilia
- albinism

Question 12

What is down syndrome

Answer 12

• has an extra chromosome in chromosome number 21
• total number chromosomes is 47
• characteristics: mental and physical disabilities, round and flat face, short neck

Question 13

What is turner syndrome

Answer 13

• has less number of sex chromosomes
• total number of chromosomes is 45 chromosomes ( 44+XO)
• a person wtih turner syndrome is a female who has a missing X chromosome
• characteristics: undeveloped secondary sexual characteristics of a female

Question 14

What is klinefelter syndrome

Answer 14

• has more number of sex chromosomes
• total number of chromosomes is 47 chromosomes (44 + XXY)
• is a male with an extra chromosome X
• chracteristics: has female characteristics like breasts, small testicles, low sperm count

Question 15

what is colour blindness

Answer 15

• unable to differentiate between red and green
• controlled by recessive genes on chromosome X
• usually occurs in males

Question 16

What is sickle-cell anaemia

Answer 16

• cause by recessive genes on the autosome
• has an abnormal red blood cell shape that is sickle-shaped that affects the transport of oxygen

Question 17

What is thalassemia

Answer 17

• the person has small, pale, red blood cells that easily burst and have short life span
• cause severe blood loss

Question 18

What is haemophilia

Answer 18

• difficulty in the clotting of the blood
• faces risk of continuous blood loss if wounded or injured

Question 19

Application of genetic research to improve quality of life

Answer 19

1) gene therapy
- repair mutant genes (abnormal) that cause disorder such as haemophilia, sickle-cell anaemia

2) forensic science
- obtain scientific evidence in criminal investigation

3) genetic genealogy
- use DNA test to determine genealogy heredity and family history

Question 20

What is recombinant DNA technology

Answer 20

• combines the DNA of 2 different species to produce a new genetic characteristic
• the production of human insulin by bacteria to help patients with diabetes

Question 21

the effects of genetic engineering technology in life

Answer 21

Advantages
1) can detect genetic failure/ familial disease and treat it
2) produce high quality yield and livestock
3) produce yield with faster growth rate and shorter harvesting period
4) increase yield and livestock

Disadvantages
1) can cause side effects or allergies to consumers
2) production of new species may cause the native species to become extinct

Question 22

What is continuous variation and discontinuous variation

Answer 22

CONTINUOUS VARIATION
shows the differences that are not distinct or not clear between individual in the same population
- determined by genetic factors but can also be affected by environmental factor
- example: height, body mass, length of fingers

DISCONTINUOUS VARIATION
- shows distinct differences between individuals of the same population
- determined by genetic factors
- example: shape of earlobes, the ability to roll tongue

Question 23

Factors that cause variation

Answer 23

GENETIC FACTOR
1) crossing over during prophasi I stage of meiosis
2) independent arrangement of chromosomes
3) random fertilisation between male and female gametes produces zygotes with different combination of geotypes
4) chromosome and gene mutation

ENVIRONMENTAL FACTORS
1) nutition
2) PH
3) temperature
4) climate
5) sunlight
6) water
example: overeating will make a person fat/ skin colour will be darker if often exposed to sunlight

Question 24

what is the importance of variation

Answer 24

• enables us to easily differentiate and recognise each individual
• anables the organisms to adapt themselves to their environment