Full mark scheme edexcel igcse biology Watch

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Trachea, Bronchus, Bronchioles (not alveoli)
b) Quote from textbook: ‘The air passages of the lungs form a highly branching network. This is why it is sometimes called the bronchial tree.’ Trachea branches out into bronchi/bronchioles a bit like a tree/large surface area
c) thorax volume increases, external intercostal muscles contract, increasing volume in thorax decreasing the pressure compared to outside air causing air to be drawn into the lungs
d) can cause fires? (i thought it was because, unlike outdoors, it’s a closed area, hence less space to diffuse and is more likely that others will breathe it in and it’s toxic etc?) i agree with (answer)
Secondary smoke is dangerous​ and lingers more without adequate ventilation; it can cause all issues related to smoking EG. Bronchitis, emphysema
Also there may be pregnant women or people with asthma
e) i thought either because they are young and growing therefore needing o2 for respiration for growth… but then i think the mark scheme may want us to talk about kids having smaller lungs?I think it was because their heart beats faster so they gotta breath faster and so they breath in and out more? So they’ll breathe in the smoke more idk (i wrote that children have less efficient respiratory systems and went on about some random BS)
Weaker immune system
Smoke might go down towards them since they’re shorter - smoke goes up
They might not realise it’s bad for them and control their breathing
in bag
Starch in water
Glucose in water
Starch alone
Starch and glucose
Starch and maltase
Starch and boiled amylase

3) genetic stuff question loved that man i remember the first was 8
give an example of a good mutationI wrote about bacteria being resistant to antibiotics. I wrote about a selective advantage( only one mark).
I put: rabbits developed mutations with large ears, which allowed them to hear better and sense predators easily, increasing their chance of survival. I got this from the Edexcel book. Disease resistant crops? You could put pests becoming resistant to pesticides
Just realised this probably had many answers guys so dw, i put mutation of peppered moth
4a) Does the father determine gender?
4b) Man a vs B.
a: More sperm healthier sperm (mutations in sperm 2 flagellums) [2]
B- more sperm -higher survival

4c) Smokers and nonsmokers graph [2]
a: 4s% of ssm=24ts
4d) Why are smokers less fertile using the graph?
a: Have less moving sperm more mutated sperm (cigarette smoke contains mutagen --> mutations.

Could affect mesophyll layer (less photosynthesis)
sd&e)Morning vs night) [2]

5a) Balanced photosynthesis equation.
a: 6H2o + 6Co2 > C6H12o6 +6o2 [1]

5b) Why are the leaves darker?
a: they have more chlorophyll because they receive less light because they're in the shade which results in a darker green colour [2]

5c) Why are the leaves thinner? [2]
a: so light can penetrate to other layers of leaves - thinner waxy cuticle (less transpiration) and smaller palisade layer; effect on rate of photosynthesis.
a: Morning = colder less light slower, more CO2 in the morning as net respiration overnight [3]
a: opposite for afternoon - less water in ground during early afternoon (evaporation / transpiration) water affects photosynthesis [3]

5f) Describe a test to compare the rate of photosynthesis for 2 plants.
a: Measure amount of o2 produced by 2 different types of pondweed with gas syringe [4]

6a) What is used?
a: Quadrat [1]

6b) Frequency of plants.
a: 8 22% [2]

6c) Number of squares plants are in.
a: 4 11% [2]

6d) How would you calculate the average for a very large field? [4]
a: Use quadrats in random area of field
Repetition to find average
Scale/Multiply by area of field

7a) Young plants in mineral solutions: describe pattern in both plants. [2]
a: in all minerals solution the plant grew to i6emm
Plants without nitrate grew to et-e8mm and began to shrink
(Lack of Nitrate ions leads to stunted growth and yellow older leaves)

7b) Why were more mineral ions absorbed when air was bubbled through
a: oxygen was needed for respiration as minerals are taken up through active transport which uses energy [3]

7c) Why was it covered with cardboard?
a: Mimic underground conditions
B: so that there is no photosynthesis of algae which could uptake the nitrates
(Prevent evaporation of water that would affect concentration gradient of mineral ions) [2]

7d)what was the dependent variable?
A: Length of the plant stem [1]

What was the independent Variable?
The question was on the dependent variable
It had both
Oh sorry meh
7e) Why was the solution sterile?
a: so no microorganisms outcompeted the plants
Micro-organisms use nutrients therefore affecting concentration of solution/competition for nutrients/no contamination [2]

8a) Draw a graph generation/cloning. [5]

8b) Describe pattern.
a: More older people supported cloning [2]

8c) Using a named example explain cloning. [6]
a: Dolly the sheep
Mature diploid
udder cell nucleus (with entire cell because sole nucleus is too fragile but this was the effect) moved into enucleated cell, stimulated to divide with an electric shock,
Implanted into uterus of surrogate sheep foster mother [5]

9a) type of neurone?
a: Nucleus [1]
B: Axon [1]
9b) Label direction of electrical impulse [1]
a: arrow going downwards on axon

9c) Describe role in the body.
a: Connects relay neuron to effector via electrical impulses [2]

9c) Differences in hormonal and nervous? [3]
a: faster/slower
small area/big area
Short-term effects/long-term effects

io) Fill in blanks:
a) cellulose starch glycogen consumer chromosome plasmid photosynthesis yoghurt pneumonia pathogen [10]

iia) How do fungi digest logs? [4]
a: saprotrophic nutrition: secrete (extracellular enzymes - needed to get mark) enzymes and absorb
iib) Design experiment to find best fungicide. (CoRMs) [6]
a: take so logs same weight surface area species
split into s groups
treat 4 groups with different fungicides leave 1 as a control
Leave all logs on forest floor: same conditions Wash to remove fungi
Weight and average groups to find loss in mass from each fungicide
Compare results

Total mark for paper [120]


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