3.1 Reproduction - STILL NEEDS SORTING

Question 1

What is mitosis?

Answer 1

• This produces genetically identical daughter cells
• These cells are diploid - they have one pair of each chromosomes in each nucleus.
• Human diploid cells have 23 pairs of chromosomes.
• Mitosis is used for growth, repair and asexual reproduction.

Question 2

What is meiosis?

Answer 2

• This produces haploid gametes which are not genetically identical
• human haploid cells have 23 chromosomes in total (unpaired)
• meiosis is only used to produce gametes for sexual reproduction

Question 3

Compare the differences of mitosis and meiosis in their processes

Answer 3

Mitosis
- produces genetically identical daughter cells
- produces two cells
- involves one cell division
- produces diploid cells in humans
- keeps the same chromosome number

Meiosis
- produces genetically NON-identical daughter cells
- produces four cells
- involves two cell divisions
- produces diploid cells in humans
- halves the chromosome number

Question 4

Compare the differences of mitosis and meiosis in their roles

Answer 4

Mitosis
- Generates all adult cells except gametes (growth & repair)
- occurs throughout the human body
- occurs throughout a plant
- used for asexual reproduction (cloning)

Meiosis
- only used to produce gametes
- only occurs in ovary and testis
- only occurs in ovary and anther
- used for sexual reproduction

Question 5

Describe cell division mitosis:

Answer 5

1. The cell grows
2. The DNA replicates to form two copies of each chromosome. These copies are joined together at a single point
3. The nuclear membrane breaks down. The chromosomes line up across the centre of the cell, attached to special spindle fibres
4. The chromatids (copies of chromosomes) are pulled apart and move to opposite ends of the cell.
5. The cytoplasm and cell membrane divides to form two identical cells.

Question 6

Describe the cell division meiosis:

Answer 6

1. The parent cell grows
2. The cytoplasm and cell membrane divides to form two identical cells.
3. The nuclear membrane breaks down. The homologous pairs of chromosomes join together
4. The homologous pairs of chromosomes exchange sections of DNA. They then attach to the spindle fibres in pairs, at the centre of the cell.
5. The homologous pairs of chromosomes are pulled apart and move to opposite ends of the cell. The cell divides.
6. The chromosomes line up along the centre of the cell, attached to the spindle fibres. The chromatids separate and move to opposite ends of the cell. Each cell divides again

Question 7

What is a diploid cell?

Answer 7

A cell that has a pair of chromosomes.

Question 8

What is a haploid cell?

Answer 8

Having chromosomes that are not in pairs.

Question 9

What is the first cell formed at fertilisation known as?

Answer 9

Zygote - contains full number of chromosomes

Question 10

What is fertilistation?

Answer 10

The fusion of haploid male and female gametes, restoring the diploid number of chromosomes in the zygote.

Question 11

What happens in the ovary?

Answer 11

Ovary - where egg cells are formed by meiosis (in the follicle). Produces the
hormones oestrogen and progesterone.

Question 12

What happens in the oviduct?

Answer 12

Oviduct - egg cells travel down this to the uterus. Lined with cilia which move
the cell. Site of fertilisation

Question 13

What happens in the uterus?

Answer 13

Uterus (womb) - a lining forms in the uterus, where the embryo will implant.
The foetus develops in the uterus, which has a thick muscular wall. This contracts during labour.

Question 14

What happens in the cervix?

Answer 14

Cervix - narrow opening to the uterus. This dilates (widens) during labour, to
allow the baby to be born.

Question 15

What happens in the vagina?

Answer 15

Vagina - muscular tube that leads from the cervix to the outside of the
woman’s body.

Question 16

What happens in the testes?

Answer 16

Testes - where sperm cells are formed by meiosis. Produces the hormone
testosterone.

Question 17

What happens in the sperm duct?

Answer 17

Sperm duct - maturing sperm are transported along this tube

Question 18

What happens in the Seminal vesicles and prostate gland?

Answer 18

Seminal vesicles and prostate gland - release liquids into the sperm duct, which mixes with the sperm cells to form semen. The liquid provides nutrients to the sperm.

Question 19

What happens in the penis?

Answer 19

Penis - transports urine and semen out of the body. Contains tissue which fills with blood to become erect; this helps to pass the semen out of the body and into the female’s vagina during sexual intercourse.

Question 20

What happens in the urethra?

Answer 20

Urethra - tube inside the penis which can transport either urine or semen.