B4 Flashcards
What is the role of the palisade layer
Photosynthesis is carried out here. They are near the top of the leaf so that they can absorb the most sunlight. They are chloroplast abundant.
What pigments are available for photosynthesis and why is there more than one pigment involved?
Pigments available : Chlorophyll a Chlorophyll b Carotene Xanthophyll Different pigments absorb different wavelengths of light, having different pigments means you can get the most of the suns energy absorbing as much as possible.
What is the role of the guard cells
Leaves have guard cells surrounding the stoma. They control when they open and closes. Allows guard cells to control gas exchange. Photosynthesis and produces glucose.
What is the balanced symbol equation
6co2+6H2O - 6O2+C6H12O6
What would happen to an animal cell if it were placed in a hypertonic solution
It would cause the cell to shrivel because it will be loosing water this cause crenation. Animals need to keep the amount of water in each cell constant.
What would happen to a plant cell if it were placed into a hypertonic solution.
It can wilt (droop) this is because everything from the cell wall has shrunk and pulled away from it. They are said to be called plasmolysed.
What does hypertonic mean
It means lots of glucose (sugar) in a solution
What are the key differences between diffusion and osmosis
Osmosis happens across a permeable wall, diffusion doesn’t
Osmosis takes place only in water
Diffusion takes place in water and gas.
What is a selective permeable membrane
It is a wall in osmosis which has wholes only small enough for water to pass through
How does transpiration keep a plant turgid
Because there’s more water inside the plant than outside it, water escapes through stomata. So if there’s lots of water available the stoma will remain open.
How does transpiration cool a plant down
The constant stream of water from the ground to keep the plant cool.
What factors affect the rate of transpiration
An increase in light intensity
An increase in temperature
An increase in air movement
A decrease in air humidity
Name three devices used to collect small animals
Pooter = small insects Pitfall = animals Net = air/water
What method and calculation would you use to determine the abundance of animals in an area
Capture-recapture Population size = no.in first sample X no.in 2 sample \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ No. In second sample previously marked
Describe in detail the process of photosynthesis
Photosynthesis uses energy from the sun to change CO2 and H2O into glucose and O2. It takes place in chloroplasts in plant cells - they contain pigments like chlorophyll which absorb light energy.
What are the products of photosynthesis used for
Glucose: respiration Lipids - storing in seeds Making proteins Making cell walls Stored as starch
How does temperature affect the rate of photosynthesis
Photosynthesis works best warm but not hot. As temp rises so does rate of photosynthesis. But if too high the enzymes become denatured making the rate decrease (45 degrees).
What is the job of the xylem
They carry water and minerals from the roots up to the shoot to the leaves in the transpiration stream.
What is the job of the phloem.
They transport food substances (mainly sugar) both up and down the stem to growing and storage tissues.
What is the movement of food substances in phloem tubes called.
Translocation
How are cacti adapted for surviving in arid (dry) conditions.
Stems that can store water.
Widespread root systems that can collect water from a large spines instead of leaves, minimise the surface area so reduce water loss by transpiration.
Why do plants need nitrates and magnesium
Nitrates - for making amino acids and proteins needed for cell growth.
Magnesium - in small amounts, required for making chlorophyll which is needed for photosynthesis
What happens if plants don’t get the nitrate or magnesium.
Plants without either will have yellow leaves and if nitrate isn’t available growth will be poor
What is active transport
Uses energy from respiration to help plant pull minerals into the root hair against the concentration gradient (from low to high)
Why is active transport unique compared to osmosis or diffusion.
It goes against the concentration gradient, low to high
What is a detritivore and give an example
They feed on dead and decaying material
An example would be earthworms, maggots and woodlice
How do saprotrophic bacteria (saprophytes) feed
By extracellular digestion
Feed by secreting digestive enzymes onto material outside of cells, enzymes break down material which are then absorbed by them.
Name two decomposes
Fungi and bacteria
Describe 3 ways of preserving food
Canning - food in airtight can, keeps decomposers out
Cooling - food in fridge, slows down decomposers reproduction rate
Freezing - food in freezer, decomposers can’t reproduce at all at such low temps
Name 2 advantages of organic and non organic farming
Organic - fewer chemicals used
Better for the environment, less chance of polluting rivers
Non organic - producing as much food as possible
Reduces energy loss in food chains
2 disadvantages for organic and non organic farming
Organic - takes up more space
You can’t grow as much food
Non organic - pesticides disturb food chains
Careless use of fertilisers can pollute rivers
What are the conditions needed for bacteria to carry out decay process effectively
Temperature- a hot temp=decay faster, it speeds up respiration in microorganisms
Amount of water makes things decay faster - when they’re moist because microorganisms need water
Amount of O2 - decay=faster with O2 available
What would happen if bacteria were deprived O2 during the decay process
The rate of decay would decrease
Microorganisms reproduce slower
What is osmosis
The net movement of water molecules across a partially permeable membrane from a higher water concentration to a lower (dilute to concentrated)
If there is more water on side b than a why do the water molecules go to side a - osmosis
Because they are trying to create a water equilibrium.
What is diffusion
Net movement of particles from a high to low concentration
