OCR A Level Biology A H420 Paper 1 6th June 2019 UNOFFICIAL MARKSCHEMEWatch
Sorry for the typo in the poll calamitous not calamatous. Any-whom.
If anyone wants use this to make a better unofficial mark-scheme feel free.
Please post your answers below and I will update accordingly. Evil Homer
====Multiple Choice (Questions 1-15) no particular order, but see the contribution at the bottom.
Thanks to reenam for the multiple choice.
1) which plant hormones cause fruit to drop
Answer: ethene and auxin
2) the question on myoglobin, adult haemoglobin and fetal haemoglobin
- myoglobin (far left -no S shape curve), fetal haemoglobin then adult haemoglobin (far right)
3) question on bacteria appearing blue and limiting factors
- i put it absorbs red light and light intensity is a limiting factor
4) evidence to show gravitropism
- roots moves down
5) when plant is put under water stress what evidence for abscisic acid role
- stomatal closure
6) diagram of pre synaptic neurone. which row correct.
- cant remember which row but vesicles dont contain ca2+, it was the axon not the dendron, and arrow pointed to the pre-synaptic membrane and mitochondria in the bulb
7) question on meristem cells, xylem cells- which is living and dead. I think xylem is dead, but meristem is living im not sure though
8) stem cells question - this was good
- ability to divide and regenerate tissue.
9) bone marrow stem cells question
- pluripotent and multipotent
- neither pluripotent nor multipotent
- multipotent but not pluripotent - i put this one because i thought bone marrow cells can only differentiate into blood cells (hence multipotent) but not pluripotent, cos that's differentiation into all kinds of cells? i acc have no clue lol.
10) Picture of a synapse where you had to label the organelles.
11) Auxins in the dark. FIll in the work section. Answer was possibly light synthesised auxin. Auxin causes cells to elongate.
12) Photosynthetic bacteria. They reflect red light.
13) Tendons in muscles features. They are flexible, insoluble, strong
14) Bone marrow stem cells. Identify what the blood cells were. Answer was probably erythrocyte, and phagocyte, definitely not that epithelial cell.
15) Aldosterone question
Multiple choice contributions in order of question number 1-15:
Rosiepointon5: C A A C D A D D C B D C D D B
Clingfilmhater: C A A C D A B D B C D C D B B
Consensus: C A A C D A ? D ? ? D C D ? B
====Written questions (assorted)
Graph on the pressure of left aorta, left atrium and left ventricle.
Compare the pressure between the left atrium and left ventricle on the tiny scale going up in 0.2s. Graph.
Percentage increase of the pressure of the left aorta: 45% (2 significant figures)
Beats per minute calculation: 60/0.7 = 86 BPM (2 significant figures)
Type of valve after percentage question: Bicuspid or semilunar
Food Tests, Colorimetry and Brown Fat:
Food tests: various things about biuret's, iodine, glucose strips insert (whatever that was for anyway). Table asking for the colours of different tests that would show (annoying as different textbooks use different colours but I'm sure the mark scheme will accommodate for this.)
Food molecule that would not show: non-reducing sugar.
How would a colorimeter improve the results?
A colorimiter improves results as is produces objective results whereas colours are a subjective result as different people can interpret them differently.
Which organelle does brown fat have more of?
-SER or mitochondria?
Circulatory systems (6 marker):
Compare and contrast the circulatory systems of mammals and fish
Fish have a single circulatory system. Heart has two chambers.
Mammals have a double circulatory system. Heart has four chambers.
Both have a closed circulatory system.
Countercurrent possible for fish?
Bodybuilders, Steroid Users and Athletic Students:
Why is the bodybuilders blood vessels showing most likely to be veins?
Large in appearance due to the large lumen of the vein..
Close to muscle tissue ( muscle contraction aids the movement of blood through veins due to it being under Low pressure)
Capillaries are too small to be that big.
Why are steroid hormones be applied to skin?
It was about how the receptors on the skin have a site that is complementary to the shape of ACh
Why athletic people have slower heart-rates?
Less plaque build up in the blood vessels?
Stronger heart muscles?
What the students should have kept constant for intensity exercise?
-level of exercise
-food intake before the exercise
etc etc etc etc...
What is a conjugated protein with reference to the Figure?
A protein with a prosthetic group (non protein part) in this case the iron ion.
Similarities and differences between haemoglobin and random protein beginning with R?
- Both contain iron?
- Globular proteins.
- Haemoglobin is a globular protein?
- Haemoglobin has 4 polypeptide chains not 1
- Haemoglobin has two beta polypeptide and two alpha
- And the other protein has disulfide bonds Haemoglobin doesn’t
Mathematics question and Technicolor Squids:
Volume occupied by iron in the sphere thing.
264nm^3 for volume not occupied by iron.
Role of the hydrophilic and hydrophobic groups
Colour changing squid
The squid question simply asked how acetylcholine could cause the colour to turn blue and then it asked for the mechanism by which the haemocyanin had a lower affinity for oxygen.
People talked about enzymes for the colour change.
Bohrs effect for affinity. Mechanism of lower affinity for oxygen caused by CO2 in the squids blood?
High pco2 means more o2 dissociation so this means that o2 is less affinities to haematocyn
Draw suitable graph for table of results
Use most of space. Is a LINE OF BEST FIT required???????
Adrenal glands and Testosterone Cheaters:
Question about the adrenal glands. They labelled the medulla and cortex as region A, B and C .
Missing answers were Aldosterone, Cortisol, or noraderenaline? Glucocorticoids were also discussed.
Which part of the adrenal gland secretes adrenaline?
The adrenal medulla?
Testosterone question (6 marker) will go here:
Analysis of the graph and conclusion drawn about the statement: The number of people cheating with testosterone in sports went down/ or counterargument.
264 though some people got 255 or near enough that value, there will be leniency.
Loads of ppl getting 36,000 for people teasing positive for testosterone and I don’t know why. The scale of the graph may have confused you.
Draw atrial fibrillation: Just draw very frequent lines.
Photosynthesis and plant hormones:
Why is gibberelin a plant hormone?
Just like the name I think I just wrote gibberish here about it being a chemical messenger.
Name one other role of gibberellins?
Control dormancy in plant seeds.
Name of enzyme in the light independent stage of photosynthesis?
Letters to do with the light independent stage of photosynthesis.
Why is it both accurate and inaccurate to refer to the light independent stage as being light independent?
It doesn’t use light in the Calvin cycle but it needs to ATP and NADP made from the light dependent reaction to work.
Two roles of auxin?
Why does the plant display the relationship (when lateral shoots don’t grow) with auxins?
Industrial use of plant hormones?
Scientist's Photosynthesis Experiment:
Variables question to do with a photosynthesis experiment.
Dependent variable: Volume of Oxygen
Variable that was not controlled: Temperature
Will promote it and get it filled in.
How did it go today guys?
What was the other similarity between Haemoglobin and the other protein?
For the letter question on photosynthesis i got:
C A A C D A D D B B D C D D B