6: Plant Nutrition Flashcards
Define photosynthesis
The process by which plants synthesise carbohydrates from raw materials using energy from light
State the word equation for photosynthesis
carbon dioxide + water —-> glucose + oxygen
in the presence of light and chlorophyll
What is chlorophyll?
green pigment found in chloroplasts
What does chlorophyll do?
It transfers energy from light into energy in chemicals, for the synthesis of carbohydrates
Outline the subsequent use and storage of the carbohydrates made in photosynthesis.
1: starch as an energy store
2: cellulose to build cell walls
3: glucose used in respiration to provide energy
4: sucrose for transport in the phloem
5: nectar to attract insects for pollination
Why are nitrate ions and magnesium ions so important?
Nitrate ions are used for making amino acids and magnesium ions are used for making chlorophyll
State the balanced chemical equation for photosynthesis
6CO2 + 6H2O —-> C6H12O6 + 602
State two characteristics of a leaf
Thin and have a large surface area
Why is it better for a plant to convert glucose into starch for storage?
Starch is more compact than glucose, and glucose dissolves very easily in water
What is the function of the waxy cuticle and how does the structure of it help its function?
function: prevents water loss from leaf tissues.
how structure helps function: Waxy material provides waterproof layer, which reduces evaporation from leaf surfaces. Thicker on upper surface (hotter/more sunlight) and thinner on lower surface (cooler/more shaded)
What is the function of the upper epidermis and how does the structure of it help its function?
function: light goes through this layer
how structure helps function: Single layer of cells with no chloroplasts so that light can pass through
What is the function of the palisade mesophyll and how does the structure of it help its function?
function: contains chloroplasts to carry out photosynthesis
how structure helps function: palisade mesophyll cells are packed tightly together to maximise light absorption
What is the function of the spongy mesophyll and how does the structure of it help its function?
function: diffuses CO2 to mesophyll cells
how structure helps function: large air spaces allow a faster rate of diffusion
What is the function of the chloroplasts and how does the structure of it help its function?
function: absorbs light
how structure helps function: there are many of them in order to absorb as much light as possible
What is the function of the air spaces and how does the structure of it help its function?
function: diffusion of gases (oxygen and carbon dioxide) and water vapour through the leaf tissue
how structure helps function: air spaces are connected directly to the outside atmosphere when the stomatal pores are open. Water vapour and gases can moe through the spongy mesophyll by diffusion down concentration gradients and pass to/from other leaf tissues
What is the function of the lower epidermis and how does the structure of it help its function?
function: allows gases to diffuse in and out
how structure helps function: has a lot of small holes called stomata which allow gases to diffuse in and out
What is the function of the guard cells and stomata and how does the structure of it help its function?
function: can open or close to allow gases (CO2 needed for photosynthesis, O2 produced) to diffuse in and out of the leaf and to allow water vapour to diffuse out
how structure helps function: can prevent gases and water vapour from diffusing out when it need it
What is the function of the xylem and how does the structure of it help its function?
function: carry water needed for photosynthesis and minerals from the roots up the stem and to the leaves
how structure helps function: cells joined into a continuous tube with end walls and cell contents removed to allow an unencumbered flow of water and minerals
What is the function of the phloem and how does its structure help its function?
function: carry organic molecules (products of photosynthesis) from the leaves or storage organs to the site they are needed
how structure helps function: Cells adapted to actively transport materials into the phloem tubes
What would happen if you added hydrogen carbonate indicator to increasing levels of CO2?
It would turn yellow as the carbon dioxide concentration increases (pH is lower)
What would happen if you added hydrogen carbonate indicator to decreasing levels of CO2?
It would change from red through pink to purple as carbon dioxide concentration falls (pH is higher)
What are the factors affecting the rate of photosynthesis?
> availability of light
the presence of chlorophyll molecules inside the leaf
a supply of carbon dioxide and water
a suitable temperature for enzyme activity
