REPRODUCTION (PLANTS)

Question 1

What are some methods of asexual reproduction?

Answer 1

Runners - sent out from the parent plant that grows a clone offspring from where the runner touches ground
Bulbs - The bases of flowers, swollen with food. Buds in these can develop into a new plant
(Potato) tubers - growing underground, from branches from the main stem
The eyes on a potato can individually produce new plants
Cuttings - A section of the plant’s stem planted in damp soil to grow roots

Question 2

What are the benefits/issues of asexual production?

Answer 2

Asexual reproduction tends to be faster, and doesn’t require multiple organisms.
Although, there is no variation between the parent and offspring, so all traits are passed on, even if negative

Question 3

How does sexual reproduction work?

Answer 3

Pollination - the transfer of pollen from an anther to stigma, so fertilisation occurs between male and female gametes
Cross-pollination - pollen and stigma are from 2 different plants, with pollination relying on insects and the wind

Question 4

What is the structure of a male reproductive system?

Answer 4

The stamen is the overall system and is made up of the anther and filament
Anther - these produce male gametes
Filament - stalk that supports the anther

Question 5

What is the structure of a female reproductive system?

Answer 5

The carpel is the overall system and consists of stigma, style and ovary
Stigma - where pollen grains attach to
Style - rod that supports the stigma
Ovary - contains eggs inside of ovules

Question 6

How are plants adapted to insect pollination?

Answer 6

Brightly coloured petals
Scented flowers
Nectaries (nectar-secreting glands)
These attract insects
Sweet-tasting fruit, so insects consume them for sugars and excrete the seeds somewhere else

Large, sticky pollen grains - these stick to insects as they go from plant to plant
Sticky stigma - any pollen from insects are picked up

Question 7

How are plants adapted to wind pollination?

Answer 7

Small, dull petals
No nectaries/strong scents
Insects don’t need to be attracted to these

Many pollen grains - small and light to be carried by the wind
Long filaments - anthers hang outside the plant, pollen is blown away by the wind
Feathery stigma - catching pollen blown by the wind; can also hang outside the plant

Question 8

What is the process of fertilisation?

Answer 8

1. Pollen grain lands on flower stigma
2. Pollen tube grows out of the grain, through the style and ovary into the ovule
3. The male gamete’s nucleus moves down the tube and joins the ovule
4. The fertilized female gamete forms a seed, while the ovary forms a fruit around the seed

Question 9

What is the process of germination?

Answer 9

Once in the soil, seeds lie dormant until optimal conditions are met:
1. Water - activating enzymes in the seed that break down food in the seed
2. Oxygen - for respiration and producing energy from the food, growing the plant
3. Good temperature - depends on the seed, but is for optimal function of the seed’s enzymes
4. Light to stimulate growth

Question 10

What is the structure of a seed?

Answer 10

A developed seed contains an embryo and food wrapped in a seed coat.
When germination occurs, respiration gets glucose from the food store, transferring energy for growth
Once enough energy has been used for leaves to grow, food and energy can be obtained from photosynthesis

Question 11

How does cross-pollination increase genetic variation?

Answer 11

Two different parent plants breeding
They have unique gametes with different genotypes
They fertilise and produce an offspring

Question 12

What are the pros and cons of germinating away from the parent?

Answer 12

Good - less competition for light, both get sufficient
Less competition for water, both get sufficient
Less competition for minerals like nitrates and phosphates

Bad - They may grow in bad conditions compared to the parent plant