Section 6- Plant Structures And Their Functions Flashcards
How are plants able to make their own food
Plants make their own food by photosynthesis
What happens during photosynthesis
During photosynthesis, photosynthetic organisms use energy from the sun to make glucose.
Photosynthetic organisms
Green plants and algae
How are some of the glucose used.
Some of the glucose is used to make larger, complex molecules that the plants or algae need to grow. These make up the organisms biomass
Biomass
The mass of living tissue.
Where does photosynthesis occur
Photosynthesis happens inside chloroplasts as they contain chlorophyll which absorbs light. Energy is transferred to the chloroplasts by light.
Equation for photosynthesis
Carbon dioxide + water = glucose + oxygen
6CO_2 + H_2_O = C_6_H_12O_6 + 6O_2
Is photosynthesis endothermic or exothernic
Endothermic, energy is taken in during the reaction
What is the rate of photosynthesis affected by
3 limiting factors which stops photosynthesis from happening any faster
- light intensity
- concentration of carbon dioxide
- temperature
How to investigate the effect of light intensity on the rate of photosynthesis
Pondweed can be used to measure the effect of light intensity on the rate of photosynthesis. The rate at which pondweed produces oxygen corresponds to the rate at which it is photosynthesising.
The faster the rate of oxygen production, the faster the rate of photosynthesis.
1. The apparatus is set up. Light source is pointing to the conical flask, the conical flash contains water and sodium hydrogen carbonate with water and Canadian pondweed. Gas syringe is joint with the with the conical flask.
2. A source of white light is placed at a specific distance from the pondweed
3. The pondweed is left to photosynthesise for a set amount of time
4. As it photosynthesises, the oxygen released will collect in the gas syringe.
5. the whole experiment is repeated with the light source at different distances from the pondweed. the rate of oxygen production at each distance can then be produced.
6. this can be calculated by: volume produced/time taken.
7. Any variables that could affect the results should be controlled.
e.g. temperature- controlled by putting the conical flask in a water bath.
Carbon dioxide concentration- adding a set amount of sodium hydrogencarbon to a set volume of water
what does sodium carbonate do
released carbon dioxide in the solution
what does the gas syringe do
allows you to measure the volume of oxygen produced
what are the limiting factors of photosynthesis
- temperature
- carbon dioxide concentration
- light intensity
how does light intensity affect the rate of photosynthesis
Not enough light slows down the rate of photosynthesis. This is because light transfers energy needed for photosynthesis.
how is the graph for light intensity and how is it described
at first, as the light level is raised, the rate of photosynthesis increases steadily as the rate is directionally proportional to light intensity. however this is only up to a certain point.
beyond this certain point it plateus so it wont make a difference meaning itll either be temperature or the concentration of carbon dioxide being the limiting factor
how do you investigate light intensity in a lab
by moving a lamp closer to or further away from the plant.
how to work out light intensity
light intensity∝ 1/(distance)^2
how does carbon dioxide affect the rate of photosynthesis
too little carbon dioxide slows down the rate of photosynthesis. carbon dioxide is one of the raw materials needed. So increasing the carbon dioxide concentration, increases the rate of of photosynthesis up to a point.
how is the graph of carbon dioxide affecting he rate of photosynthesis described
as the concentration of carbon dioxide increases the rate of photosynthesis increases up to a point. after this the graph plateaus showing that carbon dioxide is no longer the limiting factor and either temperature and light intensity are
how does temperature affect the rate of photosynthesis?
if the temperature is a limiting factor, its because its too low, the enzymes needed for photosynthesis work more slowly at low temperatures, if the plant gets too hot, the enzymes it needs for photosynthesis will denature
types of transport vessels that flowering plants have
- xylem
- phloem
what do the root hair cells do
take in minerals and water
how are root hair cells adapted to its function
- Long ‘hair’ like protrusions which stick out into the soil.
- large surface area for absorption given by the protrusions meaning it can absorb large amounts of minerals and water from the soil by using active transport
- lots of mitochondria in order to produce a lot of energy for active transport
what type of transport do root hair cells use
active transport and osmosis
why do root hair cells use active transport
the concentration of mineral ions is usually higher in the root hair cells than in the soil around them. this means that the mineral ions are absorbed by active transport
what is the issue with root hair cells
the minerals the plant needs are at a higher concentration inside the cell than outside the soil. they have to use energy for active transport against the concentration gradient.
what are the essential minerals plants need
- magnesium ions to produce chlorophyll for photosynthesis
- nitrates to produce proteins.
where does the energy that is needed for active transport come from
comes from cellular respiration which occurs in the mitochondria.
two ways that plants transport their sugars and water
TRANSPIRATION
TRANSLOCATION
translocation
how plants transport their SUGARS.
why is translocation used
plants make their own sugars by using photosynthesis. all of this occurs in the leaves, so in order to share these sugars with the rest of the plant in order to be used by energy, they have to be transported by TRANSLOCATION
what is translocation achieved by
the phloem cell
what is the structure of the phloem cell and how is it adapted
- made by elongated living cells with small pores in the end walls which allows to flow stuff through and enable the movement of cell sap
- both directions
- transports food substances mainly sucrose made in the leaves for the rest of the plant for immediate use (energy) or storage.
cell sap
a liquid mixture of water and sugar. this means that the sugars that were made in the leaves can be transported long distance through multiple cells
transpiration
how plants transport WATER
what is transpiration achieved by
the xylem. it transports both water and mineral ions from the roots UP the stem to the leaves where the water can be used for photosynthesis
what is the structure of the xylem cell and how is it adapted
- made from dead cells joined end to end with no ends between them and no walls with a hole down the middle.
- strengthened with a material called LIGNIN
- carry water and mineral ions from the roots, through xylem out of the leaves so that the water can be uses for photosynthesis.
- moved UP the xylem.
what is transpiration caused by
transpiraton is the loss of water from the plant.
1. transpiration is caused by the EVAPORATION and DIFFUSION of water from a plants surface. Most transpiration happens at the leaves.
2. the loss of water creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the XYLEM VESSEL to replace it.
3. this means more water is drawn up from the roots and so theres a CONSTANT TRANSPIRATION STREAM of water through the plant.
4. the transpiration stream carries mineral ions that are dissolved in the water along with it.
stomatas
- needed for gas exchange
- tiny pores on the surface of a plant. they are mostly found on the lower surface of leaves.
- stomata allows carbon dioxide and oxygen to diffuse directly in and out of a leaf
- allows water vapour to escape during transpiration
how is transpiration a side effect
transpiration is a side effect of the way leaves are adapted for photosynthesis. they have to have stomata so that gases can be exchanged easily. because there is more water inside the plant than in the air outside, water escapes from the laves through the stomata by diffusion
what are stomatas surrounded by
guard cells
what are guard cells
guard cells can change shape to control the size of the pore
what can the guard cells change shape into
it can be turgid or flaccid
flaccid
-low on water
- the stomata are closed
turgid
- swollen with water
- stomata are open
how is the transpiration rate affected by environmental factors
- light intensity
- temperature
- air flow
how does light intensity affect the transpiration rate
the BRIGHTER the light, the GREATER the transpiration rate. the stomata begins to close as it gets darker. this is because photosynthesis doesnt occur when it gets dark, so they dont need to open to let carbon dioxide in. when the stomata are closed, very little water can escape
how does temperature affect the transpiration rate
the WARMER it is, the FASTER the transpiration rate happens. when it is warm the water particles have more energy to evaporate and diffuse out of the stomata
how does air flow affect the transpiration rate
the BETTER the air flow around a leaf - strong wind- the greater the transpiration rate. if the airflow around the leaf is poor, the water vapour just surrounds the leaf and doesnt move away. this means theres a high concentration of water particles outisde the leaf aswell as inside it, so diffusion doesnt happen quickly.
if theres a good air flow, the water vapour is swept away maintaining a low concentration of water in the air outside of the leaf. diffusion then happens quickly, from an area of higher concentration to an area of low concentration down the concentration gradient
how does air flow affect the transpiration rate
the BETTER the air flow around a leaf - strong wind- the greater the transpiration rate. if the airflow around the leaf is poor, the water vapour just surrounds the leaf and doesnt move away. this means theres a high concentration of water particles outisde the leaf aswell as inside it, so diffusion doesnt happen quickly.
if theres a good air flow, the water vapour is swept away maintaining a low concentration of water in the air outside of the leaf. diffusion then happens quickly, from an area of higher concentration to an area of low concentration down the concentration gradient
how to estimate the transpiration rate
using a piece of apparatus
- POTOMETER
the potometer actually measures the water uptake by a plant but it is assumed that water uptake by a plant is directly related to water loss from the leaves, known as transpiration.
how to use potometer
- set up the apparatus and record the starting position of the air bubble
- start a stopwatch and record the distance moved by the bubble per unit time.
calculating the speed of the air bubble movement gives an estimate of the transpiration rate
how else can you use a potometer
you can also estimate how:
- light intensity
- temperature
- air flow
around the plant affect the transpiration rate
HOWEVER, remember to only CHANGE ONE VARIABLE AT A TIME.
