Past paper mistakes 📖📓📜 Flashcards
Fermentation is an exothermic reaction. What does the term ‘exothermic mean’? [1]
Releases energy to the surroundings
A student investigated the effect of temperature on fermentation in yeast. The apparatus aware: gas syringe, water Bath, flask, layer of oil + yeast in sugar solution.
Suggest why a layer of oil was needed on the surface of the mixture.
Hint: oxygen
To keep oxygen out
A student investigated the effect of temperature on fermentation in yeast. The apparatus aware: gas syringe, water Bath, flask, layer of oil + yeast in sugar solution.
Suggest why the mixture was left for 20 minutes, before the gas syringe was attached [1]
- the mixture was left for 20 minutes to allow the yeast cells to reach the temperature.
Malaria is transmitted by mosquitoes. Male mosquitoes are sterilised so they are infertile. The spread of malaria is reduced, by releasing sterile mosquitoes into the environment.
Explain how releasing sterile mosquitoes reduce the spread of malaria [2]
- releasing sterile mosquitoes reduces the spread of malaria because it reduces breeding in mosquitoes, so there are fewer mosquitoes to bite people.
Scientists have developed patches of beating heart cells to replace damaged heart tissue.
The patches are placed onto areas of the heart where cells have died. New cells grow to replace the dead cells. The patches are made using a person’s own cells that are converted into stem cells.
Explain why stem cells are used to make the patches. [2]
Hint: what can stem cells form?
- stem cells are used to make the patches because:
- stem cells can differentiate into any type of (specialised) cell, therefore they can form heart muscle cells.
Scientists have developed patches of beating heart cells to replace damaged heart tissue.
The patches are placed onto areas of the heart where cells have died. New cells grow to replace the dead cells. The patches are made using a person’s own cells that are converted into stem cells.
The scientists could have used human embryonic stem cells to make the patches.
Give two advantages of using the person own cells, rather than using embryonic stem cells. [2]
Two advantages of using the person’s own cells are:
- adults can give consent
- the body won’t reject them. [cells won’t be rejected].
Explain why plants with TMV grow slowly [3]
- less chloroplasts in leaves= so reduced photosynthesis, which means that less glucose is produced, so less cellulose is made.
Explain why it’s important than dissolved sugars are moved both upward and downwards in a plant. [3]
Hint: all cells need _____ from respiration
- sugars are made in the leaves by photosynthesis + all cells need sugar from respiration.
- sugars are transported to meristems for growth
Explain how sleeve tube cells are specialised for their function
Hint: movement of dissolved sugars
- no nucleus- maximises space for the movement of dissolved sugars.
Dissolved sugars are made through a plant in phloem tissue. What is the name of the process that moves dissolved sugars through phloem tissue?
Translocation
Explain how water is transported from the soil, to the atmosphere through a plant. [4]
Hint: osmosis, soil, root ____ cells, xylem vessels, leaves, stomata, atmosphere
- absorbed from soil by osmosis through root hair cells, through xylem vessels to the leaves, lost through stomata to atmosphere- driven by evaporation.
Explain why heart attack survivors get out of breath easily [4]
Hint: heart muscle ______ contract, less _____ pumped, less oxygen reaches body for _______ respiration
- heart muscle cannot contract, so less blood is pumped out of heart = less oxygen reaches body for aerobic respiration= so breathing rate increases to supply more oxygen.
Name a disease that obesity can lead to.
- high blood pressure.
