16.3 Sexual Reproduction in Plants (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
1/570Still learning
Know0
Define pollination.
Was this flashcard helpful?
Cards in this collection (57)
Define pollination.
The transfer of pollen from an anther to a stigma.
Define stamen.
The male part of a flower, made up of the anther and filament.
What are the parts of the carpel (female part of a flower)?
The carpel consists of the:
stigma
style
ovary
ovules
What is the function of the anther?
To produce and release pollen grains, which contain the male gamete.
What is the function of the stigma?
The sticky top of the female part that collects pollen grains.
Where is the male gamete of a plant found?
Inside the pollen grain, as a nucleus.
Describe three features of an insect-pollinated flower.
large, brightly coloured petals to attract insects
scent and nectar present
sticky, spiky pollen; anthers and stigma inside the flower
Describe three features of a wind-pollinated flower.
small, dull petals
no scent or nectar
large amounts of small, light, smooth pollen; anthers and feathery stigma outside the flower
The male part of a flower, the stamen, is made up of the anther and the .
The male part of a flower, the stamen, is made up of the anther and the filament.
Wind-pollinated flowers produce large amounts of small, light, pollen grains.
Wind-pollinated flowers produce large amounts of small, light, smooth pollen grains.
True or False?
Insect-pollinated flowers have large, brightly coloured petals.
True.
Brightly coloured petals attract insects to the flower to transfer pollen.
True or False?
Wind-pollinated flowers produce sticky, spiky pollen grains.
False.
Wind-pollinated flowers produce smooth, light pollen; sticky, spiky pollen is a feature of insect-pollinated flowers.
Define cross-pollination.
The transfer of pollen from one plant to the stigma of another plant of the same species.
Define self-pollination.
The transfer of pollen from a flower to its own stigma, or to another flower on the same plant.
Why does cross-pollination improve a species' chances of survival?
It increases genetic variation, so offspring are more likely to have adaptations suited to new conditions.
Why does self-pollination reduce genetic variation?
All the gametes come from the same parent, so the offspring are genetically very similar.
State one advantage of self-pollination.
The plant does not rely on pollinators, so it can reproduce where pollinators are absent.
State one disadvantage of cross-pollination.
It relies on pollinators (e.g. bees), which may be missing.
Cross-pollination transfers pollen to another plant of the species.
Cross-pollination transfers pollen to another plant of the same species.
Self-pollination the genetic variation of the offspring.
Self-pollination reduces the genetic variation of the offspring.
True or False?
Cross-pollination increases genetic variation in the offspring.
True.
Pollen comes from a different plant, mixing genetic information and increasing variation.
True or False?
Self-pollination requires two different plants.
False.
Self-pollination occurs within one plant — pollen lands on the same flower's stigma or another flower on the same plant.
Why is the decline in bee numbers important to humans?
Bees are pollinators of many food crops, so fewer bees means poorer cross-pollination and lower crop yields.
Define fertilisation in plants.
The fusion of a pollen nucleus with an ovum nucleus inside the ovule.
Define pollen tube.
A tube that grows down the style to carry the pollen nucleus to the ovule.
Why does a pollen grain grow a pollen tube?
Pollen cannot swim, so it grows a tube down the style to reach the ovum nucleus in the ovary.
Where does fertilisation take place in a flowering plant?
In the ovule, inside the ovary.
What does a fertilised ovule develop into?
A seed, containing the zygote (embryo).
What does the ovary develop into after fertilisation?
A fruit.
What is the difference between pollination and fertilisation?
Pollination is the transfer of pollen from anther to stigma; fertilisation is the fusion of the pollen and ovum nuclei.
During fertilisation, the pollen nucleus fuses with the nucleus.
During fertilisation, the pollen nucleus fuses with the ovum nucleus.
After fertilisation, each ovule develops into a .
After fertilisation, each ovule develops into a seed.
True or False?
A pollen tube grows down the style to reach the ovule.
True.
The pollen tube carries the pollen nucleus down the style so it can fuse with the ovum nucleus.
True or False?
Pollination and fertilisation are the same process.
False.
Pollination is the transfer of pollen to the stigma; fertilisation is the later fusion of the pollen and ovum nuclei.
Define germination.
The start of growth in a seed, which develops into a plant.
Define cotyledon.
A seed structure that stores food reserves to supply the young seedling until it can photosynthesise.
Define testa.
The seed coat, which splits when the seed germinates.
What are the plumule and the radicle?
The plumule is the first emerging shoot; the radicle is the first emerging root.
What is the function of the cotyledons during germination?
They provide food (energy) for growth until the seedling grows leaves and can photosynthesise.
What three conditions are needed for germination?
water
oxygen
warmth
Why is water needed for germination?
It makes the seed swell and splits the testa, and activates the enzymes needed for growth.
Why is oxygen needed for germination?
For respiration, to release the energy needed for growth.
During germination, enzymes convert stored in the cotyledons into soluble sugars.
During germination, enzymes convert stored starch in the cotyledons into soluble sugars.
The first root to emerge from a germinating seed is called the .
The first root to emerge from a germinating seed is called the radicle.
True or False?
Warmth is needed for germination because it allows enzymes to work.
True.
Germination is controlled by enzymes, which work too slowly at low temperatures.
True or False?
Carbon dioxide is required for a seed to germinate.
False.
Germination needs water, oxygen and warmth; carbon dioxide is not required.
Define seed dispersal.
The distribution of mature seeds away from the parent plant.
Why do plants disperse their seeds away from the parent?
To prevent overcrowding and reduce competition, and to colonise new habitats.
Give two methods of seed and fruit dispersal.
wind
animals
Describe the adaptations of a wind-dispersed fruit or seed.
Parachute- or wing-shaped and lightweight, with a large surface area so they are carried by air currents.
How are seeds in fleshy fruits dispersed by animals?
The fruit is eaten and the seeds pass through the gut, leaving in the faeces away from the parent.
How are hooked or sticky seeds dispersed?
They catch onto the fur or feathers of passing animals and are carried away.
What is the difference between pollination and seed dispersal?
Pollination is the transfer of pollen from anther to stigma; seed dispersal is the distribution of mature seeds.
Seed dispersal reduces between offspring and the parent plant.
Seed dispersal reduces competition between offspring and the parent plant.
Wind-dispersed seeds are light and have a large to be carried by air currents.
Wind-dispersed seeds are light and have a large surface area to be carried by air currents.
True or False?
Seed dispersal reduces competition between a plant and its offspring.
True.
Dispersal spreads seeds away from the parent, reducing competition for water, light and nutrients.
True or False?
Brightly coloured fleshy fruits are an adaptation for wind dispersal.
False.
Brightly coloured fleshy fruits are eaten by animals — they are an adaptation for animal dispersal, not wind dispersal.
Sign up to unlock flashcards
or