3.1 Reproduction - animal and plant

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.
• 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
  -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: mitosis

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

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 fertilisation in animals?

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 in animals?

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 in animals?

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 (animals)?

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.

Question 21

Sexual reproduction in plants. How does it occure?

Answer 21

produces genetically varied offspring using specialised sex cells called gametes
3 steps to occur:
pollination, fertilisation and germination

Question 22

Asexual reproduction in plants.

Answer 22

produces genetically identical offspring
gametes are not needed and there is only one parent involved
the offspring are called clones

Question 23

When is sexual reproduction in plants an advantage?

Answer 23

in a changing environment
or when there is a threat of disease from pathogens

Question 24

When is asexual reproduction in plants an advantage?

Answer 24

in a stable environment because it allows parent plants with advantageous adaptions to produce offspring with the same beneficial characteristics

Question 25

What are the natural methods of asexual reproduction in plants?

Answer 25

runners - a new plant is produced where the runner touches the ground tubers - swollen underground stems containing lots of stored food --> one plant can produce many tubers which can each grow many shoots which form new plants bulbs - underground buds with thick fleshy leaves containing stored food --> a main shoot will grow out of the side 'daughter' bulb, forming two plants

Question 26

What is the artificial method for asexual reproduction in plants?

Answer 26

cuttings - a piece of a plant's stem, with a few leaves attached, is cut from a healthy plant this is planted in damp compost, where it will grow roots and develop into a new plant

Question 27

What are the gametes in plants and where are they produced?

Answer 27

pollen - is the male gamete and is produced in the anther, which is part of the male part (stamen) of the flower Ova - is the female gamete and is produced in the ovules, which is found in the ovary withing the female part of the flower (carpel)

Question 28

What are the features of insect pollinated plants?

Answer 28

stamens: enclosed within flower stigma: enclosed within flower and sticky petals: large and brightly coloured nectaries: present - produce sugary liquid to attract insect

Question 29

What are the features of wind pollinated plants?

Answer 29

stamens: exposed outside of petals stigma: exposed outside of petals, often 'feathery' petals: small, usually green nectaries: absent

Question 30

What are the steps for pollination and fertilisation?

Answer 30

- In plants pollen grains are deposited onto the stigma. - The pollen grain normally grows a pollen tube which grows down through the style. - Enzymes are secreted at the tip of the tube which digest the tissues of the style. - When the tube reaches an ovule the male gamete travels through the tube entering the ovule through a small hole called the micropyle. - It then fuses with the female gamete (ovum) in the process of fertilisation. - The fertilised ovum divides by mitosis to form the embryo - The ovule develops into the seed. - The ovary develops into the fruit

Question 31

fruit formation

Answer 31

The ovule wall becomes the seed coat, or Testa (the hard coating of the seed) The ovary wall becomes the fruit coat

Question 32

What do plants need in order to germinate?

Answer 32

oxygen - to aerobically respire warmth - optimum temperature for enzymes water - to activate the enzymes

Question 33

Investigating the conditions needed for germination

Answer 33

Cress seeds are added to cotton wool in test tubes - Tube A is put in a fridge (no warmth) and the rest are kept on a windowsill. - In tube C, the cotton wool is moistened with boiled water and an oxygen absorber such as sodium pyrogallol is added (no oxygen). - Tube E is wrapped in foil (no light). - The cotton wool in tube B is kept dry (no water). - Tube D has all the conditions present. - Check for germination after 2-3 days - you could combine class results and calculate % germination or mean length of seed for each condition.

Question 34

Compare the differences of mitosis and meiosis in their processes: meiosis

Answer 34

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

Question 35

What is the function of the placenta?

Answer 35

allows nutrients and oxygen to move from the mother to the embryo Metabolic wastes move from the embryo to the mother

Question 36

What is amniotic fluid and its role during pregnancy?

Answer 36

protects the baby from: any bumps drying out temperature fluctuations