Reproduction In Plants & Animals

Question 1

What is sexual reproduction?

Answer 1

The process involving the fusion of two gametes to form a zygote, with genetically different offspring.

Question 2

What are advantages & disadvantages of sexual reproduction?

Answer 2

Advantages - increased genetic variation & lower disease impact

Disadvantages - time & energy to find mates

Question 3

What is asexual reproduction?

Answer 3

The process resulting in genetically identical offspring being produced from one parent

Question 4

Through which process do bacteria produce genetic copies of themselves?

Answer 4

Binary fission

Question 5

What are advantages & disadvantages of asexual reproduction?

Answer 5

Advantages - rapid population increase & more energy efficient

Disadvantages - limited genetic variation & more likely impact of disease

Question 6

Describe the process of fertilisation?

Answer 6

Male & female gamete fuse together to form a zygote which undergoes cell division to form an embryo.

Question 7

Describe the features of insect-pollinated plant?

Answer 7

Petals - bright to attract insects
Scent - to attract insects
Number of pollen grains - moderate
Pollen grains - large/sticky to attach to insects
Anthers - stiff - brush against insects
Stigma - sticky so pollen sticks from insects

Question 8

Describe the features of a wind-pollinated flower?

Answer 8

Petals - dull
Scent - none
Number of pollen grains - large
Pollen grains - smooth - easily blown
Anthers - swinging loose outside
Stigma - outside flower & feathery - catch pollen grains

Question 9

What is cross-pollination?

Answer 9

Pollen from one plant transferred to stigma of another plant from the same species
- genetic variation

Question 10

What is self-pollination?

Answer 10

Pollen landing on its own stigma
- reduced genetic variation as all gametes from same parent

Question 11

Why is lack of genetic variation disadvantageous?

Answer 11

Less likely offspring will have adaptations suitable to new conditions

Question 12

How does pollination occur?

Answer 12

Pollen (male gamete) lands on the stigma (female gamete)

Question 13

What is an ovum?

Answer 13

An ovum is an egg cell that contains the female nucleus

Question 14

When does fertilisation occur in plants?

Answer 14

When the pollen grain nucleus fuses with the ovum nucleus

Question 15

Describe the growth of the pollen tube?

Answer 15

Pollen grain grows a pollen tube.
Nucleus inside pollen grain moves down the tube as the tube grows down the style towards the ovary.
When the pollen grain’s nucleus & the ovum nucleus have fused - zygote formed - develops into an embryo plant.

Question 16

Describe seed & fruit formation?

Answer 16

After fertilisation, ovule develops into seed.
Ovule wall develops into seed coat (testa).
Flower parts surrounding ovule (ovary walls) develop into fruit.
The fruit provides a mechanism for seed dispersal.

Question 17

Why do different fruits have different numbers of seeds?

Answer 17

Different plants have a different numbers of ovules.

Question 18

What factors are needed for successful germination?

Answer 18

Water – allows seed to swell up – seedcoat bursts – embryo exits the seed.
Oxygen – respiration – energy released for germination.
Warmth - reactions are controlled by enzymes.
CO2 makes no difference.

Question 19

How do germinating seeds utilise food reserves?

Answer 19

Cotyledons surround embryo.
Cotyledons contain food reserves - supply seedling with food (+energy) - until plant grows its own leaves & can photosynthesise.

Question 20

What happens when the seed takes in water?

Answer 20

The seed coat (testa) splits & produces plumule & radicle (1st emerging shoot & root).

Question 21

Describe asexual reproduction through runners?

Answer 21

Natural method:
Plants grow side branches (runners) with small plantlets.
When they touch the soil, plantlets grow roots & new plantlets grow & become independent from the parent plant.

Question 22

Describe asexual reproduction through cuttings?

Answer 22

Artificial method:
Take cuttings from a parent plant.
Placed into water until roots grow or soil & planted - grow into identical adult plants.

Question 23

Describe how the male reproductive structures are adapted?

Answer 23

Prostate gland - produces semen
Sperm duct - sperm passes through
Urethra - ring of muscle prevents urine/semen mix
Testis - produces sperm
Scrotum - ensures sperm slightly lower temperature
Penis - pass out semen

Question 24

How is the female reproductive system adapted?

Answer 24

Oviduct - ciliated cells to push released ovum
Ovary - contains ova that develop when hormones released
Uterus - where fertilised egg implanted to develop
Cervix ring of muscle to keep foetus in place
Vagina - where sperm deposited

Question 25

Where does fertiliser occur?

Answer 25

Oviduct

Question 26

Explain the adaptations of the sperm?

Answer 26

Flagellum - swims to the egg
Head enzymes - digests jelly coat of egg
Many mitochondria - respiration energy so flagellum moves back & forth

Question 27

Explain the adaptations of an egg?

Answer 27

Cytoplasm - provides energy for dividing zygote
Jelly coating - barrier after fertilisation to prevent other sperm entering

Question 28

Explain the role of the placenta in the nutrition of the developing embryo?

Answer 28

Foetus’ blood connects to & from placenta by umbilical chord.
Placenta acts as a barrier to prevent toxins & pathogens getting into baby’s blood.

Question 29

Which substances moves across the placenta?

Answer 29

To mother - CO2 & urea
To baby - glucose, amino acids, oxygen, water

Question 30

How is the placenta adapted?

Answer 30

Large SA & thin wall for efficient diffusion.

Question 31

What is the placenta?

Answer 31

Organ that ensures materials can be exchanged between blood of mother & blood of growing embryo.

Question 32

How does the amniotic fluid protect the growing embryo?

Answer 32

By cushioning it from bumps to the mother’s abdomen.