Plants as Organisms Flashcards
1
Q
What happens when roots grow towards moisture?
A
- more auxin is produced on the side with more moisture
- this inhibits growth on the side, causing the root to bend in that direction, towards moisture
2
Q
What factor is limiting at night, winter and during warm and bright times?
A
- night: light
- winter: temperature
- warm and bright: CO2
3
Q
Where is auxin produced?
A
- it is produced in the tips
- it moves backwards to stimulate cell elongation which occurs in the cells just behind the tips
4
Q
What is cross pollination?
A
- when pollen is transferred from the anther of one plant to the stigma of a different plant
5
Q
What is the equation for photosynthesis?
A
- carbon dioxide + water → glucose + oxygen
- 6CO2 + 6H2O → C6H12O6 + 6O2
6
Q
Explain the stages of plant fertilisation
A
- the anther produces the male gametes in pollen grains
- a pollen grain lands on the stigma
- a pollen tube grows out of the pollen grain, down through the style to the ovary and into the ovule
- a nucleus from a male gamete then moves down the tube into the ovary where it fertilises the egg cell nucleus in the ovule. the two nuclei fuse to make a zygote, which then divides by mitosis to form an embryo
- at the same time other nucleir from the male gametes fertilise endosperm nuclei in the ovule. this produces the endosperm, a food sac that stores starch to feed the growing embro
- the endosperm plus the female tissues of the ovule make up a seed. the ovary develops into a fruit around the seed
7
Q
What is transpiration?
A
- transpiration is caused by the evaporation and diffusion of water inside the leaves
- this creates a slight shortage of water in the leaf, so more water is drawn up from the rest of the plant through the xylem vessels to replace it
- this means more water is drawn up from the rooots, so there is a constant transpiration stream of water through the plant
- water moves out of the plant through the stomata by osmosis because there is higher water potential inside
8
Q
What do xylem tubes do?
A
- made of dead cells joined end to end with no end walls between them and a hole in th emiddle
- they carry water and minerals from the roots to the stem and leaves
- this is called the transpiration stream
9
Q
Where does photosynthesis happen?
A
- in the leaves of all green plants
10
Q
How do plants use glucose?
A
- respiration: plants manufacture glucose in their leaves. this releases energy which enables them to convert the rest of the glucose into other useful substances.
- making cell walls: glucose is converted into cellulose for making strong cell walls
- making proteins: glucose is combined with nitrate ions to make amino acids, which make proteins. the Venus Fly Trap are adapted to live in nutrient pooor soils as they get their nutrients from animals
- stored as fats or oils: glucose is conveted to lipids for storing in seeds
- storing as starch: glucose is turned inro starch and stored in roots, stems and leaves, to use for when photosynthesis isnt happening, such as in winter. starch is insoluble, making it better for storing.
11
Q
What does auxin do?
A
- it controls the growth of a plant in response to phototropism, geotropism and hydrotropism
12
Q
Label the parts of a flower’s reproductive system
A
Stamen (male reproductive part)
- anther: contains pollen grains these produce the male gamestes
- filament: the stalk that supports the anther
Carpel (female reproductive part)
- stigma: the end bit that the pollen grains attach to
- style: the rod-like section that supports the stigma
- ovary: contains the female gametes inside ovules
13
Q
What happens in flowering plants?
A
- carbon dioxide diffuses into the air spaces within the leaf then it diffuses into the cells where photosynthesis happens. it leaves by diffusion through the stomata
- most of the water and mineral ions are absorbed by the roots
14
Q
What are the stomata?
A
- holes underneath the leaf where plants obtain carbon dioxide from the atmosphere and remove oxygen in photosynthesis
- most of the water vapour loss takes place thorugh the stomata. evaporation is more rapid in hot, dry and windy conditions
- if the plant loses water faster than it is replaced by roots, the stomata can close to prevent wilting
15
Q
Explain the fertilisation of plants
A
- anther produces the male gametes in pollen grainss
- a pollen grain lands on the stigma, the top of the female carpel
- a pollen tube grows out of the pollen grain, down through the style, to the ovary and into the ovule
- a nucleus from a male gamete then moves down the tube into the ovary where it fertilises the egg cell nucleus in the ovule. it forms a zygote, which then forms an embryo as is divides by mitosis
- at the same time, other nuclei from the male gametes fertilise endosperm nuclei in the ovule. this produces endospem, a food sac which stores starch to feed the growing embryo
- endosperm plus the female tissues of the ovule make up a seed. the ovary develops into a fruit around the seed
