Combined Science A (Gateway) · OCR J250 · Biology Paper 8 · Higher · June 2019
In 2008 there were 16 600 people with liver disease. Of these, 600 survived liver disease due to a liver transplant.
Calculate the percentage of people with liver disease who survived because of a liver transplant in 2008.
A 3.6%
B 3.7%
C 26.7%
D 27.7%
[1]
Look at the sperm cell.
The eye can see objects 0.1 mm.
What minimum magnification will be needed before the eye can see the head of this sperm cell?
A 0.167×
B 1.67×
C 16.7×
D 167×
[1]
A genetic cross occurs between a heterozygous individual and a homozygous recessive individual.
What is the probability of these individuals having offspring that are homozygous recessive?
A 0 in 4
B 1 in 4
C 2 in 4
D 3 in 4
[1]
The graph shows the annual number of cancer cases worldwide and the number of cases triggered by HPV infections.
From evidence in the graph, which cancer is linked most strongly to HPV infections?
A Cervical cancer
B Vaginal cancer
C Mouth cancer
D Throat cancer
[1]
Which is the best technique to investigate the effect of shade from a tree on the types of plants growing in a field?
A Capture-recapture
B Line transect
C Pitfall traps
D Quadrat sampling in a grid
[1]
Look at the diagram of part of the nitrogen cycle.
What is happening at X?
| Conversion | |
| A | Amino acids to nitrogen |
| B | Nitrates to amino acids |
| C | Nitrates to nitrogen |
| D | Nitrogen to nitrates |
[1]
MRSA is a type of bacteria that cannot be treated with most antibiotics.
How has MRSA developed?
A Genetic engineering
B Natural selection
C Protein synthesis
D Selective breeding
[1]
Look at the effects of mercury waste from a factory.
The fishermen became ill.
What is the most likely explanation for this?
A Mercury builds up in the food chain.
B Mercury in the seawater gets onto their hands.
C Mercury kills their food supply.
D They breathe in mercury vapour fishing near the factory.
[1]
The graph shows the survival rates for two groups of patients diagnosed with ≥ 50% blockage of a coronary artery. One group was treated with surgery, the other group were treated with medication.
How many years after diagnosis was there the biggest difference in survival rates between the two types of treatment?
| Years after diagnosis | |
| A | 2 – 4 |
| B | 6 – 8 |
| C | 10 – 12 |
| D | 13 – 15 |
[1]
New drugs are tested using preclinical trials.
Which statement describes a preclinical trial?
A One group of volunteers are given a placebo, another group the drug.
B The drug is tested on human cells.
C Volunteers are given a placebo only.
D Volunteers are given the new drug.
[1]
Water is cycled in nature.
Name one abiotic factor that affects water uptake by a plant.
[1]
Look at the diagram of the carbon cycle.
Which process is shown by arrow X in the diagram?
Tick (✓) one box.
[1]
Which process releases carbon when organisms die ?
Tick (✓) one box.
[1]
The graph shows how carbon dioxide levels in the atmosphere have changed during the last 160 000 years.
Read this statement:
Carbon dioxide levels in the atmosphere are rising out of control.
What evidence is there in the graph for and against this statement?
[2]
Look at the section of the graph for the last 20 000 years.
What conclusion can be made about the release of carbon dioxide into the atmosphere and also its removal from the atmosphere during the last 20 000 years?
[2]
Describe how human activity has contributed to the trends in the graph and suggest how this activity could affect biodiversity.
[3]
The information in the box is part of a scientific journal report.
Growing crops with shiny leaves could cause an annual global cooling of over 0.1 °C.
This is almost 20% of the total global temperature increase since the Industrial Revolution.
Most crop plants have non-shiny leaves.
A few varieties of crop plants do have shiny leaves but they do not all produce high yields.
Explain how scientists could use selective breeding to help reduce global temperatures.
[2]
12* (a) Look at the diagram, it shows how humans, Homo sapien s, evolved.
It also shows that humans are closely related to other apes, like chimpanzees.
Describe how humans, Homo sapiens, evolved from Australopithecus afarensis and the evidence for this shown in the diagram.
[6]
Describe how the use of DNA in phylogenetics has changed classification systems.
[2]
How does the structure of DNA support its use in phylogenetics?
[2]
HIV is a virus that causes AIDS.
Some countries have set up centres where a person is counselled and tested for HIV.
The aim is to reduce new infections by 50%.
Write down two types of testing that can be done to identify someone with HIV.
[2]
Humans who contract HIV do not die from the virus. Instead they die from AIDS-related diseases such as tuberculosis (TB).
HIV infects human cells by inserting genes into the cells. The human cells then copy the genes.
TB is caused by bacteria that infect the lungs.
Explain why a person with HIV is more likely to die from TB than a person without HIV.
Use ideas about the immune system in your answer.
[4]
HIV can be transmitted during unprotected sexual intercourse.
Name one method of contraception and explain why it prevents the transmission of HIV.
Name of method of contraception........
Why it prevents the transmission of HIV........
[2]
Scientists are trying to develop a vaccine against HIV.
Explain how a vaccine could protect people against HIV.
[3]
Which type of medication can be used to treat people who already have HIV?
[1]
Plant material decomposes to make compost.
Gardeners add compost to their soil to increase crop yield.
Give one reason why compost increases crop yield.
[1]
Gardeners use compost activator to speed up the decomposition of plant material.
Compost activator contains bacteria.
Scientists are developing a new compost activator. To do this they need to isolate samples of bacteria.
They prepare agar jelly plates containing streaks of different bacteria. Fig. 14.1 shows a scientist preparing an agar jelly plate.
In Fig. 14.1 the scientist uses a sterile glass rod to transfer the bacteria.
Suggest why this is better than just pouring the liquid directly from the bottle.
[2]
Some bacteria grow faster at 37 °C than at 25 °C.
The scientist chooses to grow the bacteria at 25 °C.
Suggest why this would be safer than growing them at 37 °C.
[2]
What is the final dilution factor in tube five ?
[1]
The scientist puts 1 ml from each tube onto a separate agar plate.
The scientist then leaves the bacteria to grow so that the bacterial colonies become visible.
They use this formula to calculate the number of bacteria in the original sample:
number of bacteria in the original sample = number of CFU in sample × dilution factor
There are 29 CFU grown from the sample taken from tube 5.
Calculate the number of bacteria in the original sample.
Give your answer in standard form.
Number of bacteria in the original sample =........ CFU per ml
[2]
The diagram in Fig. 15.1 shows events that occur during human sperm production.
Cells in the germinal epithelium have the ability to turn into sperm cells.
Which term describes cells that have the ability to turn into specialised cells?
[1]
Compare the number of chromosomes in human germinal epithelium cells and human mature sperm cells.
[1]
Describe the events that occur at Stage 1 and Stage 2 in Fig. 15.1.
[2]
Sperm production occurs best at 35.0 °C due to the enzymes involved.
Explain why the testes are positioned outside of the body cavity.
[2]
The paper as printed
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