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Provisional Mark Scheme For Edexcel IGCSE Biology Paper One 17th may 2016

Hope everything went well for you all: Trying to pull together as many known correct answers as possible and I'm certain I will miss questions so do add in your answers if you are rather sure you got them right! Do comment if some of these are wrong.

(Question) [Given Words]

1. Vacuole, Cell Wall, Chloroplasts
b) Receptor (sensory) Relay Neurone, Motor Neurone, Effector / Response
bi) (Gap between relay and motor neurone?) Synapse
c) 3/400th of a second or 0.0075 seconds

2. Fish spike in 1990s reach 66 million tonnes - Beef has a smaller range from 1950s to 2012 and fluctuates a lot more with some decreases in a million each year. Generally both a positive gradient of increased production

i) (Calculation In 2020 fish production will be Six times 1990 rate - how many fish?)
13 million tonnes in 1990 so X 6 = 78 Million Tonnes in 2020

b) Fish proteins broken down by pepsin or protease in stomach to form simple Proteins, Also digested by Low pH Hydrochloric acid found in stomach and some pummelling and ,technical digestion from stomach

c) (Table of what protein structures do what)
Insulin made in pancreasAmylaseAntibodies made in Lymphocyte3. Cars, engines, factoriel anything that run on fossil fuels
b) Sulphur Dioxide, CFCs or Water Vapour
c) Percentage decrease of 16 percent

4. Methane decreases with a range of 2.5 starting at 4.6 million tones in 1990 decreasing to 2.1 million tones in 2010

5.Ice caps melt, Extinction of polar bears or wildlife
Thinner Greenhouse gas layer so less global warming
better air quality with a higher oxygen to greenhouse gas ratio
less carcinogens or disease bearing particulates in the air

6. CORMS method (Describe an Experiment)

7. Graph

b) Describe your graph

8. Thistle

b) The bird name

c) A= Pupil
B= Iris

d) Conjuctiva, Sclera or Cornea (up for debate as all protect eye in one way or another)

Optic Nerve

Lens

9. [Fill in the gap question]
Explant, [genetically] identical, Sterilise, Bacteria, Growth [medium], starch, Chlorophyll, Nitrates, can't remember the rest

10. A population is the number of same species within an ecosystem / area

b) Describe the changes in populations of the snail colours with reference to natural selection: referencing these words will get you the marks:
Mutation
Variation
Gene
DNA
Phenotype
Black shell preyed upon
grey shell is a genetic mutation and survives 'more' or 'better' than black shell
Grey shell passes its genes on
White shell mutation is the most effective and these genes pass on
Black genes extinct, grey rare
All happens over a Number of generations

[Question Added]

(How do stomata allow For transport)
Guard Cells Open
Water diffuses out of stomata through transpiration (High conc to low conc outside)
This then create a lower conc of water in the spongy mesophyll (leaf)
High conc of water in xylem of plant / stem
Water moves from this area of high conc to area of new low conc in leaf

[Question Added]

(How do Stomata Allow Gas exchange) -
diffusion through open stomata of co2 for photosynthesis -
excretion of o2 as biproduct of photosynthesis -
diffusion- define

[Question Added]

(Why does Wind create more transpiration / water loss from leaf?)

There is a high conc. of Water inside the leaf
Low conc. in the air outside
diffusion of water occurs to outside
The wind then moves this saturated air away from the plant
New dry air arrives at the leaf
Another conc. gradient is set up as the dry air has no water in so low conc
but high conc. in leaf and transpiration occurs again
process / cycle repeats



11. (children doing exercise)
a) 136.1 BPM (average heart rate whilst exercising)

b) Thomas was the anomaly

c) Heart rate slightly increases just before exercise due to adrenaline being secreted from the adrenal gland causing heart rate to increase. (could mention excitement causes the adrenaline)

d) (Two things to keep the same) [mention two]

Length of ExerciseAge of Children / bmi of children

Time measuring heart rate

Same temperature / time of day

12. (Runners and Cyclists lower resting BPM Question)
The heart muscle is stronger as it is exerted more often, hence more blood can be pumped in the same number of beats, reducing the need for their heart to pump blood at a high frequency.

13. Protoctist - all x except for cytoplasmBacteria - tick for cell wall, plasmid,cytoplasm x for nucleusfungus - tick for cell wall, nucleus, cytoplasm x for plasmid

b) [protoctists, Fungi, Bacteria - name one more pathogen] Virus

c) (Protoctist disease?) Malaria

14.
i) Oviduct or Fallopian Tube

ii) Ovaries

iii) Uterus Lining

iv) Vagina

15. (Label diagram with O for Ovulation and M for menstruation)

O was the first peak and M was the second peak on the graph

b) Oestrogen causes the thickening or building up of the uterus lining
Progesterone then causes blood to build up through the build up of capillaries in the uterus lining
If Fertilised egg is not implanted the Uterus Lining passes out of the vagina

16. (Question on Why is Sex off period not always a reliable method of contraception)
Women menstrual cycles, whilst predictable can sometimes be different to what they are normally and the sperm (because there are so many of them) will always make it to the fillopian tube where fertilisation takes place because there is no condom or barrier method to stop them. women won't know if they are ovulation, only know of period, so the sperm could fertilise an egg.

b) (What does Oestrogen do in puberty?) [Any Three From]

Widening Of Hips

Slight gradual Lowering Of Voice

Pubic Hair

Ovulation Begins

c) (Which Parent determine babies Sex?)

Father, as a sperm carry either an X or a Y set of chromosomes and because a women;s chromosomes are always XX, the egg is always carrying a set of an 'X'chromosomes so the sperm can create an XX (female) or XY (Male) baby.

d) (Differences Between Meiosis and Mitosis) [Mention]

Mitosis creates two daughter cells
Meiosis creates four daughter cells
Mitosis creates genetically identical cells
Meiosis creates Genetically different cells due to the 'crossing over' process
Mitosis creates two new cells with 46 / a full set of chromosomes
Meiosis creates four new cells with 23 / half a set of chromosomes
Mitosis creates Diploid Cells
Meiosis creates Haploid Cells

Good Luck for the rest of you GCSEs, Will be back for Paper Two!
(edited 7 years ago)

Scroll to see replies

Reply 1
The diagram was
Cytoplasm, Nucleus, Plasmid and Wall
I think
Q 13c:
instead of phagocyte, i put lymphocyte, as in the description it said "binds to pathogen" and the phagocyte engulfs the pathogen. Also, i put white blood cells in the 3rd column, as in haemoglobin, it put red blood cell. But for everything else really similar answers.
1c. was 0.0075 - 90/12000
2c. antibodies - made in lymphocytes (not certain but lots got this)
3c. I got around 16% (15.97..) change over original x100
Reply 4
At 15., O was for ovulation, which was after the oestrogen peak, and M was for menstruation, which was at the beginning of the graph.
I think the percentage change was 16?
Also 13 I think there was more than one tick, I got
Protoctist - all x except for cytoplasm
Bacteria - tick for cell wall, plasmid,cytoplasm x for nucleus
fungus - tick for cell wall, nucleus, cytoplasm x for plasmid
cant remember last one
Reply 7
Original post by nuria_alberola
Q 13c:
instead of phagocyte, i put lymphocyte, as in the description it said "binds to pathogen" and the phagocyte engulfs the pathogen. Also, i put white blood cells in the 3rd column, as in haemoglobin, it put red blood cell. But for everything else really similar answers.


The first column of the table said "Protein". Neither lymphocytes nor phagocytes are proteins: they are cells. Antibodies bind to the antigens, and they are proteins, so the answer should be antibody, and lymphocyte for place where it is made.
Wasnt 11 a 136.1 instead of 131.1
Reply 9
Original post by Cheekymonkey2311
I think the percentage change was 16?


Yes!!!!
Cheers guys editing in your answers now
I put that the way to measure the change for the egg cell was through cell division through meiosis with different temperatures etc can that be correct?
Aha
(edited 7 years ago)
Answer was antibodies/lymphocytes for question about binds to antigens, and similar to haemoglobin being found in red blood cell, the antibodies/lymphocytes are produced by white blood cells
Reply 14
For the vagina questions, what did you put for the last label? Vagina??
Original post by nunu10
For the vagina questions, what did you put for the last label? Vagina??


Dumb me put cervix for some reason 😂😂
THANK YOU SO MUCH FOR THIS! :smile: I put Antibody and Lymphocyte for that protein table (don't know if i'm right though) and I wrote Carbon Dioxide for 3(b) - Is that right or did it have to be one of the 3 you mentioned?
Reply 17
I did the natural seletion question wrong way round. Will i get 0?
Original post by Olijones100
Answer was antibodies/lymphocytes for question about binds to antigens, and similar to haemoglobin being found in red blood cell, the antibodies/lymphocytes are produced by white blood cells


Well said babes x
I think it was sclera instead of iris as the arrow was pointing to the white part of the eye.