Difficult Topics Paper 2 Flashcards
(29 cards)
What are some conservation schemes?
Protecting a species’ natural habitat
Protecting species in safe areas
outside of their natural habitats and introduce captive breeding programmes to increase their numbers
What are the advantages of maintaining biodiversity?
Protecting the human food supply
Ensuring minimal damage to food chains
Providing future medicines
Culture
Ecotourism
Providing new jobs
How can farmers increase the amount of nitrates in the soil?
Crop rotation with at least one nitrogen-fixing crop
Spreading animal manure or compost on fields recycles the nutrients left in plant and animal water and returns them to the soil through decomposition. Artificial fertilisers containing nitrates can also be used, but these are expensive
How does fish farming decrease biodiversity?
Food is added to the nets to feed the fish which produce huge amounts of waste. Both the food and the waste can leak into the open water, causing eutrophication and the death of wild species
Fish farms in open water often act as a breeding ground for a large number of parasite
Animals can get trapped in the nets
Sometimes farmed fish can escape into the wild, which can cause problems for wild populations of indigenous species
What are the 5 stages of the nitrogen cycle?
Nitrogen fixation
Nitrification
Assimilation
Decomposition
Denitrification
What are 4 examples of biological factors that affect the level of food security
Increasing consumption of meat and fish, and increasing animal farming
Environmental changes caused by human activity
Sustainability
New pests and pathogens
What is thermal desalination?
Salt water is boiled in a large enclosed vessel, so that the water evaporates. The steam rises to the top of the vessel, but the salts stay at the bottom.
The steam then travels down a pipe from the top of the vessel and condenses back into pure water
What is reverse osmosis?
Salt water is first treated to remove solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane
The pressure causes the water molecules to move in the opposite direction to osmosis- from a higher salt concentration to a lower salt concentration
As the water is forced through the membrane, the salts are left behind, removing them from the water
What happens when legume plants containing nitrogen fixing bacteria decompose?
When these plants decompose, the nitrogen stored in them and in their nodules is returned to the soil. Nitrogen containing ions can also leak out of their nodules during pant growth. The plants have a mutualistic relationship with the bacteria. The bacteria get food from the plant and the plant gets nitrogen containing ions from the bacteria to make proteins
How can you use indicator species to measure pollution?
- Doing a simple survey to see if a species is present or absent from an area- not good for telling how polluted an area is
- Counting the number of times an indicator species occurs in an area will give you a numerical value, allowing you to see roughly how polluted one area is in comparison with another
What are some examples of non-living indicators to measure pollution?
Dissolved oxygen meters and chemical tests shows the level of water pollution
Electronic meters and various laboratory tests are also used to accurately measure the concentration of sulfur dioxide in the air
What is compost?
Decomposed organic matter that is used as a fertiliser for crops and garden plants
Why do compost bins create the ideal conditions for decomposers?
They have mesh sides to increase oxygen availability
The decomposing material is kept moist and heat is generated by the decomposers themselves
Some compost bins are insulated to increase temperature
What are the properties of capillaries?
Very narrow, so they can squeeze into the gaps between cells. This means they can carry the blood really close to every cell in the body to exchange substances with them
They supply food and oxygen, and take away CO2
Thin cell wall - one cell thick. This increases the rate of diffusion by decreasing the distance over which it occure
Permeable walls, so substances can diffuse in and out
What is fick’s law?
Rate of diffusion is directly proportional to:
SA X Concentration difference/thickness of membrane
How can you measure the rate of respiration?
1) Add some soda lime granules to two test tubes. Soda lime absorbs the CO2 produced
2) A ball of cotton wool is placed above the soda lime in each tube. Woodlice are placed on top of the cotton wool in each tube. Glass beads with the same mass as the woodlice are used in the control tube instead of woodlice
3) The respirometer is then set up going into both test tubes
4) The syringe is used to set the fluid in the manometer to a known level
5)The apparatus is then left for a set period of time in a water bath set to 15C
6) During this time, there’ll be a decrease in the volume of the air in the test tube containing the woodlice. This is because the woodlice use up oxygen in the tube as they respire. (The CO2 they produce is absorbed by the soda lime so it doesn’t affect the experiment)
7) The decrease in volume reduced the pressure in the tube, causing the coloured liquid in the manometer to move towards the test tube containing the woodlice
8) The distance moved by the liquid in a given time is measured. This value can then be used to calculate the volume of oxygen taken in by the woodlice per minute. This gives you the rate of respiration
9) Repeat steps 1-8 with the water bath set at different temperatures. This will allow you to see how changing the temperature affects the rate of respiration
What effects does adrenaline have on the body?
Adrenaline binds to specific receptors in the heart. This causes the heart muscle to contract more frequently and with more force, so heart rate and blood pressure increase
This increases blood flow to the muscles, so the cells receive more oxygen and glucose for increased respiration
Adrenaline also binds to receptors in the liver. This causes the liver to breakdown its glycogen stores, to release glucose
This increases the blood glucose level, so there’s more glucose in the blood to be transported to the cells
What happens if the blood glucose concentration is too low?
When blood glucose levels fall too low, it’s detected by the pancreas.
This causes the pancreas to release the hormone glucagon into the blood stream.
This hormone then travels around the body, and binds mainly to cells in the liver.
This stimulates those liver cells to break down their stored glycogen into glucose and release it into the blood.
This extra glucose increases blood glucose levels back up to normal.
What happens when you’re too hot?
Erector muscles lie flat
Lots of sweat is produced in sweat glands in the dermis. The sweat is released onto the surface of the skin through pores in the epidermis which evaporates and transfers energy from your skin to the environment
Blood vessels close to the surface of the skin widen causing vasodilation. It allows more blood to flow near the surface so it can transfer more energy into the surroundings
What happens when you’re too cold?
Erector muscles contract. Hairs stand on end to trap an insulating layer of air
Very little sweat is produced
Blood vessels near the surface of the skin constrict (vasoconstriction). This means less blood flows near the surface, so less energy is transferred to the surroundings
You shiver, increasing your rate of respiration which transfers more energy to warm the body
How can progesterone be used as a contraceptive?
It stimulates the production of a thick cervical mucus, which prevents any sperm getting through the entrance to the uterus (the cervix) and reaching the egg
How is the hypothalamus responsible for thermoregulation?
The hypothalamus contains receptors that are sensitive to the blood temperature in the brain. It also receives impules from receptors in the skin that provide information about the external temperature. These receptors are located in the epidermis. When the hypothalamus detects a change it causes a response in the skin
How does a dialysis filter work?
A dialysis machine can be used to filter their blood for them
Dialysis fluid has the same concentration of salts and glucose as blood plasma (which means those aren’t removed from the blood)
The selectively permeable barrier is permeable to things like ions and waste substances, but not big molecules like proteins. So the waste substances move across the membrane into the dialysis fluid.
What are xylem tubes made of?
Xylem tubes are made of dead cells joined end to end with no end walls in between them and a hole down the middle, they are strengthened by liginin
