B3 Revison Questions For Chapter Flashcards
What part of an enzymes makes it specific to a particular substrate?
The unique active site.
Explain how temperature affects enzyme activity.
A higher temperature increases the rate of reactions at first, but if it gets too hot the enzyme is denatured and the active site changes shape, so the substrate can’t fit any more.
State two ways you could measure the rate of enzymes controlled reaction
You could measure how fast a product appears or how fast a substrate disappears
Where in a plant cell does photosynthesis take place?
Photosynthesis happens inside subcellular structures called chloroplasts
What is the equation for photosynthesis?
Carbon dioxide + water. —light —->glucose +oxygen
In the inverse square law, how are light intensity and distance linked?
See p36
What effect would a low carbon dioxide concentration have on the rate of photosynthesis?
CO2 is one the substrates needed for photosynthesis, too little carbon dioxide slows down photosynthesis.
Define the following terms:
A) diffusion
B) osmosis
C) active transport
A)movement of particles from an area of high concentration to an area of low concentration.
B)movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration.
C)movement of particles across a membrane against a concentration gradient using energy transferred during respiration.
Why do multicellular organisms such as plants need specialised exchange surfaces?
Because some cells are deep inside the organism, it is a long way from them to the outside environment, so specialised exchange surfaces are needed to aid transport.
If a potato cylinder is placed in a solution with a very high sucrose concentration, what will happen to the mass of the potato cycling ear over time? Explain why.
See.p39
What is translocation?
The movement of food substances around a plant.
Which type of plant transport vessel is made up of dead cells?
Xylem tubes.
How do stomata open and close?
Stomata are surrounded by guard cells, which change shape to control the size of the pore. When the guard cells are turgid (swollen with water) the stomata are open, when the guard cells are flaccid (low on water and limp) the stomata are closed.
Give three factors that affect transpiration rate.
An increase in light intensity
An increase in temperature
An increase in air movement
Give two resources that plants compete for in ecosystems.
Water, light, space, minerals from soil, seed dispersers and pollinators.
Briefly describe how you could use quadrats to investigate the population size of a species.
See p45
What is an indicator species and why might you sample one?
See p47
How do food webs show interdependence?
Interdependence means that a change in the size of one population will affect the sizes of other populations in the community.
What does each bar on a pyramid of biomass represent?
Show mass of living material at that stage of the food chain
True or false? Producers always go at the top of a pyramid of biomass.
False. Producers are at the start if the food chain.
Why are you unlikely to see a food chain with 10 trophic levels?
Insufficient biomass, because biomass is lost at each trophic level there wouldn’t be enough biomass to support 10 levels.
Name a big molecule that’s formed from simple sugars.
Long chain carbohydrates
Which two molecules are produced when lipids are broken down?
Fatty acids and glycerol
How would you test for the presence of lipids in a sample?
See p52
Name two processes that put Carbon back into the air in the Carbon cycle.
Burning fossil fuels Burning products made from animals and plants Co2 released from decay Plant respiration Animal respiration
What is the role of microorganisms in the Carbon cycle?
Decomposers, breakdown waste and dead material.
Fungi and bacteria release CO2 back into air by respiration as they break down material.
Give three factors that affect the rate of decomposition.
Water content
Oxygen levels
Temperature
