Edexcel GCSE Biology Paper 2 - Things i got wrong

Topic 1 - Key concepts in biology, Topic 6 - Plant structures and their functions, Topic 7 - Animal coordination, control and homeostatis, Topic 8 - Exchange and transport in animals, Topic 9 - Ecosystems and material cycles

Which indicator species indicate clean water?

• Stonefly

• Freshwater shrimps

Which indicator species indicate polluted water?

Bloodworm

Sludgeworm

What indicator species indicate clean air?

Blackspot fungus on roses, Bushy lichen

How is potable water produced?

Reverse osmosis (lower to higher concentration)

What are two features of xylem vessels?

• Thick wall

• One continuous hollow tube made of dead cells called lignin

What does the xylem transport and by what process does it do this?

Water and mineral ions via transpiration

What does the phloem transport and by what process does it do this?

Sugars like sucrose via translocation which is up and down the plant. The phloem contains living cells as it needs energy from respiration to transport sugars up and down the plant.

What structure is found in veins but not arteries?

Valves

Why may energy be lost between different trophic levels in a pyramid of biomass?

• Energy is used for movement

• Energy is transferred to the surroundings through heat loss

• Respiration

What do decomposers in the soil convert?

Urea into ammonia

What does nitrifying bacteria convert?

Ammonia into nitrates

What does nitrogen fixing bacteria convert?

Nitrogen gas in the atmosphere into ammonia

How does crop rotation increase nitrate levels in the soil?

Leguminous plants contain nitrogen fixing bacteria in their root nodules which convert atmospheric nitrogen into ammonia which nitrifying bacteria convert into nitrates in the soil

What do plants need nitrates for?

Nitrates are needed to make proteins for growth

What are the three plant hormones?

• Auxins - the growth hormone

• Gibberellins - germination

• Ethene - fruit ripening

What are the commercial uses of auxins?

• Selective weed killers as they target broad leaf plants and kill them by causing them to overgrow while leaving the narrow leaf crops

• Rooting powders as they are added to the end of plant cuttings to stimulate the growth of roots

What are the commercial uses of gibberellins?

• to stimulate germination in dormant seeds

• initiate breakdown of starch

• stimulate flower formation

• promotes fruits formation

• sprayed onto plants before pollination

• stimulate development of seedless fruits

What are the commercial uses of ethene?

Unripe fruit is harvested and ethene is sprayed on them before selling to ripen the fruit at the most desired time

Wha effect does adrenalin cause?

• Adrenalin binds to receptors on liver cells

• Stimulates the breakdown of glycogen into glucose to be released into the blood

• Increased heart rate

• increased blood flow to the muscles

• Increased blood pressure

• This is done to induce the fight or flight response to protect yourself when in danger

What is Fick’s Law?

What happens to excess amino acids in the blood?

They get broken down into urea in the liver

What is eutrophication?

• Nitrates from fertilisers leak into nearby rivers

• This causes nitrate levels in the water to increase and oxygen levels in the water to decrease

• The high nitrate levels causes an overgrowth of algae

• This blocks sunlight from the plants in the water

• Plants in the water die as they can’t photosynthesise

  and are decomposed by microorganisms/decomposers which use the oxygen in the water for respiration

What is the inverse square law?

How does increased air movement affect the rate of transpiration?

• Water vapour is removed from around the leaf

• Increased rate of evaporation of water from leaf

• Plant draws up more water to leaves from stem and root

• Increased rate of transpiration

How does increased temperature affect the rate of transpiration?

• Higher temperature

• More evaporation of water from leaves

• More water drawn up to the leaves via stem and roots

• Increased rate of transpiration

How does a decrease in humidity affect the rate of transpiration?

• Less humidity means lower concentration of water molecules in the air outside the leaves

• This means that there is more diffusion of water from inside the leaves to outside of the leaves as the water moves via osmosis along the concentration gradient from a region of higher concentration in the leaves to a region of lower concentration outside of the leaves

• More water loss from the leaves causes more water to be drawn up the plant to the leaves via the stem and roots

• Increased rate of transpiration

How does an increase in light intensity affect the rate of transpiration?

• Increase in light intensity means that there is an increase in the number of open stomata

• This causes more water loss via evaporation from the leaves

• This causes the plant to draw up more water to the leaves via the stem and roots

• Increased rate of transpiration

What are the features of an atery?

• Thick, muscular wall to maintain blood pressure

• Narrow Lumen

What are the features of a vein?

• Valves to prevent the backflow of blood

• Wide lumen as lower blood pressure

What is type 1 diabetes?

When the person’s pancreas doesn’t produce any insulin

What is type 2 diabetes?

When the person doesn’t produce enough insulin or their liver has become resistant to insulin so the liver doesn’t break down glucose into glycogen

How do you calculate BMI?

How do you calculate the cardiac output?

cardiac output = stroke volume x heart rate

What is an abiotic factor and give examples?

A non-living component of an ecosystem that influences the living organisms and ecosystems within it e.g. water, temperature, light intensity, air quality

What is a biotic factor and give examples?

A living organism that affects the population of other organisms in an ecosystem e.g. competition, predators, diseases

What is a mutualistic relationship?

A relationship where two organisms depend on each other for survival

Why is sodium hydrogen carbonate used in the pondweed photosynthesis practical?

It increases the carbon dioxide concentration in the water to provide carbon dioxide for the plant to use for photosynthesis so that carbon dioxide isn’t the limiting factor of the photosynthesis practical as it is used to measure how light intensity affects the rate of photosynthesis