9b plants (biology) Flashcards
photosynthesis definition
a process that occurs in plants (and some other organisms) that involves a series of chemical reactions that convert ligtht energy into food called ‘glucose’
word equation for photosynthesis
carbon dioxide + water –> glucose + oxygen
number equation for photosynthesis
6CO2 + 6H20 –> C6H12O6 + 6O2
chlorophyll definition
a green chemical that absorbs energy transferred by light and uses it to power photosynthesis (it is the pigment that makes plants green)
reactants definition
the raw materials required for photosynthesis to occur
limiting factors definition
the factors that limit the rate of speed of photosynthesis
fill in the blanks: 1. _______ and 2. _______ are needed for photosynthesis to occur.
- energy, 2. chlorophyll
the energy transferred by light is stored in the…
glucose
what is the test for starch?
iodine solution – if starch is seen on a leaf, the plant is going through photosynthesis
what is the test for carbon dioxide?
lime water – lime water becomes milky when carbon dioxide is shaken/bubbled through it
what is starch?
starch is a carbohydrate and a product of photosynthesis that stores energy
xylem cells definition
the vascular tissue/vein that transports water throughout a plant’s body (made out of hollow dead cells)
wilt definition
when plants become weak and begin to bend towards the ground
what is the process of plants getting water?
- water is taken out of the soil by the roots/root hair cells
- water flows up xylem cells to the leaf
how are roots adapted to their function?
by being branched and spread out to help them to absorb water from a large volume of soil
why do plants need water to stay healthy?
water contains mineral salts (e.g. plants need nitrates to make proteins)
how are root hair cells adapted to their function?
by having a large surface area to help them absorb water quickly
what happens to plants when they don’t have enough water?
they wilt
how does water prevent plants from wilting?
by filling up their cells (giving the plant structure) and keeping their leaves cool
stomata definition
specialised pores or opening present in the upper epidermis of plant cells
what controls the gas exchange in a plant?
stomata
stomata function
air, containing carbon dioxide, diffuses into leaves through small holes called stomata
why do leaves have a large surface area?
to absorb as much light as possible
where does most photosynthesis occur?
in the palisade cells near the upper surface of the leaves
what do palisade cells contain?
chloroplasts (an organelle)
what do chloroplasts contain?
chlorophyll
increasing the amount of ______ can speed up photosynthesis (give an example)
reactants (e.g. water, carbon dioxide, light)
name 4 limiting factors
light intensity, water, temperature, carbon dioxide concentration
aerobic respiration definiton
a series of chemical reactions where plant cells release the energy stored in the glucose
word equation for aerobic respiration
glucose + oxygen –> carbon dioxide + water
number equation for aerobic respiration
C6H12O6 + 6O2 –> 6CO2 + 6H20
when does aerobic respiration occur?
constantly
glucose definition
a type of sugar
phloem vessels definition
the vascular tissue of a plant that carries foods made in the leaves during photosynthesis to all other parts of the plant
name 3 functions of glucose
glucose can be used for…
1. respiration to release energy
2. making other substances that act as stores of energy (e.g. starch), which can be turned back into glucose for respiration when needed
3. making new materials for growth
name 3 examples of how glucose can be used for making new materials for growth
- cellulose to make cell walls
- lipids to make cell membranes
- proteins to make enzymes
yield definition
an amount produced of an agricultural or industrial product
biodiversity definition
the variety of all living things and their interactions
what do modern farming methods cause?
environmental problems
why is land cleared of hedges and trees and what problems does this cause?
to make more land for crops and to make it easier for machinery to move around –> destroys habitats … lack of roots can cause soil erosion
what are 1. pesticides, 2. herbicides and 3. insecticides?
- pest killers, 2. weed killers, 3. insect killers
pesticides are used
to kill pests that compete with or harm the crops –> can kill useful organisms and pests + damages food webs
fertilisers are used
they contain mineral salts that help plants to grow and increase the yield –> can was into streams and rivers and cause pollution so that the organisms in the water die
varieties
varieties of plants are chosen that produce the highest yield –> the planning of huge areas of a single variety reduces biodiversity
selective breeding process
- farmers and plant breeders ‘select’ a plant with the certain characteristics they want
- this organism is used to breed from
- the offspring that have the best of these characteristics are bred from again
cross-breeding definition
when two different varieties are bred together to try and produce offspring with characteristics from both varieties
