Edexcel IGCSE BIOLOGY B2 2017 Unofficial Markscheme Watch

eesaali128
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Edexcel IGCSE Biology Paper 2B Unofficial Markscheme

Question 1 - Comprehension

How does increased eating of lipids contribute to heart disease(3)
cholesterol buildup
Blocks coronary artery
Cannot aerobically respire, must anaerobically respire which produces lactic acid and causes heart attack

Name two soluble molecules that form part of a balanced diet? (2)
Glucose, Vitamin A/C/D, /amino acids

Draw a food chain of the organisms: (2)
Plankton -> Anchovies -> Larger Fish (e.g. Salmon)

Why are fish stocks declining? (2)
Many fish being removed from the ocean
Fewer small fish for larger fish to eat
Overfishing due to demand by rising population
Being caught quicker than they can breed

How are enzymes used during Genetic Modification? (2)
Restriction Enzymes cut out DNA from source organism and cut out part of plasmid
Ligase enzymes mix them together to form recombinant DNA

How is a named vector used during Genetic Modification? (2)
plasmid/virus

Question 2 - The Eye

How does this part of the eye stop damage to the retina in bright light? (2)
Iris
Reflex action
Circular muscles contract, radial muscles relax, pupil gets smaller
Less light enters the eye

Why would damage to this part of the eye make it difficult to see?
Optic Nerve
Sends electrical impulses to the brain
Damage means that the brain can’t properly form an image so becomes difficult to see

Question 3 - Seed Germination

How can you tell germination has taken place
roots and shoots grow out of the seed

B) How do the seeds survive before photosynthesis
Ovule turns into food store
Glucose for respiration for energy to grow




Question X - Homeostasis
A Homeostasis
B M1; Sweat secreted
M2; Skin cooled
M3; By evaporation (using heat
from body)

C M1; Vasodilation
M2; Blood closer to skin
M3; Heat loss by radiation

D Osmoregulation
E Kidney

1. Less oxygen to muscle cells, less aerobic resp, more anaerobic, Moreno lactic acid and enzymes denature

Glucose
Amino acids
Or salts

Buyoncy and energy reserve

Glycerol

Planktons --> anchovies ---> salmon

People eat fish, so less less fish. Less Wild anchovies for wild salmon and fish Farming more popular

Energy loss via movements and excretion. Not all of it is eaten. Not all energy transferred

Restriction and ligase, cuts dna

Plasmid and viral vector, transport DNA

Circular muscles contract, pupil constricts And less light enters

Optical nerve damage meaning that's electrical impulses are dodgy

Less light enters due to cataracts and light isn't focused onto the retina therefore decrease in ability but to see

26 million

Some of rats are cured so therefore lansterol has an effect on cataracts - use figures


The rat’s lenses are much smaller than that of a human, therefore lansterol may have a greater effect.
We cannot accurately calculate the impact lansterol has had on the Rat’s vision.
Humans might react different to lansterol

Anther/Pollen?/ stamen?

Break down starch reserves into glucose for repsiration

B - temp for optimum ph Water to activate enzymes, oxygen for ph

Haemoglobin and transport oxygen

Phagocyte

Help blood to clot

Plasma /

Memory cells easy four marker
- Surface Antigens
- Lymphocyte
Faster rapid release of antibodies
Means human is not harmed or affected by virus




Homeostaisis

Sweat glands secrete sweat and water evaporate and heat transfers

Capillaries vasodialate, more blood and faster rate of heat transfer

Osmoregulation /
Kidney/ NOT HYPOTHALAMUS THIS IS NOT AN ORGAN

Organism that contain DNA from different species

E.g. Pigs providing organs for transplants / or Human Quantity of Antibodies

Genetically the same, any time of year, farmers don't have to wait until breeding season, infertile animals can be cloned, can produce lots of animals with the desired characteris like antibodies rapidly . share the same immunities as the parent.

Cloning - reduces organ transplant shortage.
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JMR2019.
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(Original post by eesaali128)
Edexcel IGCSE Biology Paper 2B Unofficial Markscheme

Question 1 - Comprehension

How does increased eating of lipids contribute to heart disease(3)
cholesterol buildup
Blocks coronary artery
Cannot aerobically respire, must anaerobically respire which produces lactic acid and causes heart attack

Name two soluble molecules that form part of a balanced diet? (2)
Glucose, Vitamin A/C/D, /amino acids

Draw a food chain of the organisms: (2)
Plankton -> Anchovies -> Larger Fish (e.g. Salmon)

Why are fish stocks declining? (2)
Many fish being removed from the ocean
Fewer small fish for larger fish to eat
Overfishing due to demand by rising population
Being caught quicker than they can breed

How are enzymes used during Genetic Modification? (2)
Restriction Enzymes cut out DNA from source organism and cut out part of plasmid
Ligase enzymes mix them together to form recombinant DNA

How is a named vector used during Genetic Modification? (2)
plasmid/virus

Question 2 - The Eye

How does this part of the eye stop damage to the retina in bright light? (2)
Iris
Reflex action
Circular muscles contract, radial muscles relax, pupil gets smaller
Less light enters the eye

Why would damage to this part of the eye make it difficult to see?
Optic Nerve
Sends electrical impulses to the brain
Damage means that the brain can’t properly form an image so becomes difficult to see

Question 3 - Seed Germination

How can you tell germination has taken place
roots and shoots grow out of the seed

B) How do the seeds survive before photosynthesis
Ovule turns into food store
Glucose for respiration for energy to grow




Question X - Homeostasis
A Homeostasis
B M1; Sweat secreted
M2; Skin cooled
M3; By evaporation (using heat
from body)

C M1; Vasodilation
M2; Blood closer to skin
M3; Heat loss by radiation

D Osmoregulation
E Kidney

1. Less oxygen to muscle cells, less aerobic resp, more anaerobic, Moreno lactic acid and enzymes denature

Glucose
Amino acids
Or salts

Buyoncy and energy reserve

Glycerol

Planktons --> anchovies ---> salmon

People eat fish, so less less fish. Less Wild anchovies for wild salmon and fish Farming more popular

Energy loss via movements and excretion. Not all of it is eaten. Not all energy transferred

Restriction and ligase, cuts dna

Plasmid and viral vector, transport DNA

Circular muscles contract, pupil constricts And less light enters

Optical nerve damage meaning that's electrical impulses are dodgy

Less light enters due to cataracts and light isn't focused onto the retina therefore decrease in ability but to see

26 million

Some of rats are cured so therefore lansterol has an effect on cataracts - use figures


The rat’s lenses are much smaller than that of a human, therefore lansterol may have a greater effect.
We cannot accurately calculate the impact lansterol has had on the Rat’s vision.
Humans might react different to lansterol

Anther/Pollen?/ stamen?

Break down starch reserves into glucose for repsiration

B - temp for optimum ph Water to activate enzymes, oxygen for ph

Haemoglobin and transport oxygen

Phagocyte

Help blood to clot

Plasma /

Memory cells easy four marker
- Surface Antigens
- Lymphocyte
Faster rapid release of antibodies
Means human is not harmed or affected by virus




Homeostaisis

Sweat glands secrete sweat and water evaporate and heat transfers

Capillaries vasodialate, more blood and faster rate of heat transfer

Osmoregulation /
Kidney/ NOT HYPOTHALAMUS THIS IS NOT AN ORGAN

Organism that contain DNA from different species

E.g. Pigs providing organs for transplants / or Human Quantity of Antibodies

Genetically the same, any time of year, farmers don't have to wait until breeding season, infertile animals can be cloned, can produce lots of animals with the desired characteris like antibodies rapidly . share the same immunities as the parent.

Cloning - reduces organ transplant shortage.
Could I say gene instead of DNA here
'Restriction Enzymes cut out DNA from source organism and cut out part of plasmid
Ligase enzymes mix them together to form recombinant DNA'
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eesaali128
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(Original post by JMR2017)
Could I say gene instead of DNA here
'Restriction Enzymes cut out DNA from source organism and cut out part of plasmid
Ligase enzymes mix them together to form recombinant DNA'
yeah that should be fine considering it is only one gene theyre taking out
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