Reproduction and Inheritance - Reproduction

Question 1

what is sexual reproduction?

Answer 1

fertilisation of two sex cells to form a zygote which will develop into a non-identical offspring

Question 2

what are the advantages of sexual reproduction?

Answer 2

• increases variation
• offspring can adapt to new environment
• disease is less harmful to the population

Question 3

what are the disadvantages of sexual reproduction?

Answer 3

• time consuming
• needs two partners

Question 4

what is asexual reproduction?

Answer 4

reproduction by a single parent to produce genetically identical offspring via mitosis

Question 5

what are the advantages of asexual reproduction?

Answer 5

• rapid increase in population
• can thrive in a suitable environment

Question 6

what are the disadvantages of asexual reproduction?

Answer 6

• no variation
• vulnerable to change in the environment as they don’t adapt
• disease is more harmful to the population

Question 7

what is fertilisation?

Answer 7

the fusion of a male and female gamete to produce a diploid zygote that undergoes mitosis to develop into an embryo

Question 8

what structures do flowers contain?

Answer 8

sepals, petals, stamens (filament and anther), and pistils (stigma, style and ovule)

Question 9

what are the sepals?

Answer 9

leaf-shaped structure on the outermost part of a flower that protects an unopened flower

Question 10

what are the petals?

Answer 10

brightly coloured leaves surrounding the reproductive part of the flower to attract pollinators

Question 11

what is a stamen?

Answer 11

male part of the flower, containing the filament and the anther
filament - slender stalk supporting the anther to make it accessible to pollinators
anther - lobes on top of the filament that produces the male gamete (pollen)

Question 12

what is a pistil?

Answer 12

female part of the flower, containing the stigma, style and ovule
stigma - sticky, receptive tip that catches the pollen
style - tube-shaped connection that elevates the stigma to catch pollen
ovule - contains female reproductive cells that develop into a seed after fertilisation

Question 13

how are insect-pollinated flowers adapted?

Answer 13

• petals are large and brightly coloured to attract pollinators
• nectar is scented to attract pollinators
• moderate amount of pollen grains as insects are efficient pollinators
• pollen grains are sticky and spiky to attach to insect
• stigma is stick to catch pollen when brushed against insect

Question 14

how are wind-pollinated flowers adapted?

Answer 14

• petals are small and dull
• nectar is unscented
• large amount of pollen to increase chances of pollination
• pollent grains are smooth and light to be easily carried by the wind
• anthers are outside the flower to release pollen via wind
• stigma is feathery and outside the flower to catch pollen grains

Question 15

how is a seed formed in a plant?

Answer 15

• pollen grain lands on the stigma
• pollen tubes grows down the style until it reaches the ovule in the ovary
• nucleus of pollen grain passes along the pollen tube to fuse with the nucleus of the ovule
• ovule develops to form a seed, ovule wall forms the seed coat

Question 16

what conditions are needed for seed germination?

Answer 16

water - needed to activate enzymes to break down food reserves
oxygen - aerobic respiration
warmth - optimal enzyme production

Question 17

how would you investigate the conditions needed for germination?

Answer 17

• cotton wool is placed at the bottom of four boiling tubes, each containing five cress seeds
• test tube a: moist cotton wool and placed in a warm environment (all conditions/control)
• test tube b: dry cotton wool and placed in a warm environment (no water)
• test tube c: moist cotton wool and placed in a cold environment (no warmth)
• test tube d: cotton wool soaked in boiled water that is cooled off, and layered with oil on top (no oxygen)
• cress seeds in each respective test tube are allowed to adjust for a fixed number of days

Question 18

how do germinating seeds get nutrition?

Answer 18

• absorption of water during germination triggers the production of plant hormones, stimulating the production of amylase
• amylase breaks down food reserves until seedling can carry out photosynthesis

Question 19

how can plants reproduce asexually by natural methods?

Answer 19

• cells split off from the parent plant to grow side branches called runners
• the runners grow roots and the plant will evolve, forming a genetically identical plant

Question 20

how can plants reproduce asexually by artificial methods?

Answer 20

• cutting of plant is taken and sterilised
• cutting is grown in a petri dish containing sterile nutrient agar gel
• explant is treated with growth hormones
• root and shoot develop and cloned plant can be transferred to the soil

Question 21

what does the male reproductive system contain?

Answer 21

the bladder, sex gland, sperm duct, urethra, testis and penis

Question 22

what is the bladder?

Answer 22

a muscular sac that stores urine before it is expelled

Question 23

what is the sex gland?

Answer 23

gland that secretes semen

Question 24

what is the sperm duct?

Answer 24

long tube that transports sperm from testes to be mixed with fluids in sex gland

Question 25

what is the urethra?

Answer 25

tube that transports semen from sex gland/urine from baldder to outside the body

Question 26

what is the testis?

Answer 26

two oval-shaped organs held outside the body by the scrotum to synthesize sperm and testosterone

Question 27

what is the penis?

Answer 27

passes urine and semen out of the body

Question 28

what does the female reproductive system contain?

Answer 28

the bladder, the oviduct, the ovary, the uterus, the cervix, the urethra and the vagina

Question 29

what is the oviduct?

Answer 29

tube that transports released ovum from the ovary to the uterus for fertilisation

Question 30

what is the ovary?

Answer 30

tissue where egg cell matures before ovulation

Question 31

what is the uterus?

Answer 31

where fertilised egg cell will be implanted to develop into fetus

Question 32

what is the cervix?

Answer 32

ring of muscle that closes to protect the developing fetus and opens to form the birth canal

Question 33

what is the vagina?

Answer 33

a muscular passage leading to the uterus by which the penis can enter

Question 34

what happens in the first stage of the menstrual cycle?

Answer 34

day 1 - menstruation starts. the uterine lining breaks down for about 4 days

Question 35

what happens in the second stage of the menstrual cycle?

Answer 35

the uterus lining builds up again from day 4 to 14, into a thick spongy layer ready to receive a fertilised egg

Question 36

what happens in the third stage of the menstrual cycle?

Answer 36

an egg develops and is released from the ovary at day 14 (ovulation)

Question 37

what happens in the fourth stage of the menstrual cycle?

Answer 37

the wall is maintained from day 14 to day 28. if no fertilised egg had landed on the uterus wall by day 28, the spongy lining starts to break down

Question 38

how does oestrogen control the menstrual cycle?

Answer 38

1. produced in the ovaries
2. causes the uterus lining to grow
3. stimulates the release of LH

Question 39

how does progesterone control the menstrual cycle?

Answer 39

1. produced in the ovaries by the remains of the follicle after ovulation
2. maintains uterus lining during the second half of the cycle. when progesterone falls the uterus lining breaks down
3. inhibits the release of LH and FSH

Question 40

what happens once the embryo has implanted?

Answer 40

the placenta develops, which lets the blood of the embryo and mother get very close to allow the exchange of food, oxygen and waste

Question 41

what is the amnion membrane?

Answer 41

it forms after the embryo has implanted. it surrounds the embryo and is full of amniotic fluid, which protects the embryo from knocks and bumps.

Question 42

what are the effects of oestrogen?

Answer 42

development of secondary sexual characteristics (development of breasts, growth of body hair, beginning of menstrual cycle)

Question 43

what are the effects of testosterone?

Answer 43

development of secondary sexual characteristics (growth of penis, growth of facial and body hair, voice breaking, sperm production)