Biology 5090 · O Level
Oct/Nov 2021
98 questions from this paper, with worked solutions and instant marking.
The diagram shows the cell structures of a human liver cell, a leaf palisade cell and a human red blood cell. Which cell structure is X?
Cell structure and function
The diagram shows a cross-section through a villus. Which products of digestion are mainly taken up by vessel X?
Absorption and assimilation
The diagram presents a transverse section of a plant stem. Which process causes substances to be transported in region Z?
Transpiration and translocation
Which statement accounts for why a leaf wilts?
Transpiration and translocation
In what ways are veins different from arteries?
Blood vessels
The diagram illustrates a simplified human circulatory system. Which structure is the heart?
Heart
The diagram illustrates the pressures on the left side of the heart during one heartbeat. At the time labelled X, which valves are open and which are closed?
Heart
Many processes in the body need energy. Which process is carried out without using energy?
Diffusion and osmosis
What characteristics do the alveoli have?
Human gas exchange
Which graph illustrates a person’s breathing pattern while resting and then during exercise?
Human gas exchange
During kidney dialysis, which blood components move out of the blood into the dialysis fluid?
Urinary system
Which process takes place by diffusion only?
Diffusion and osmosis
What biological process is shown in the diagram?
Diffusion and osmosis
The diagram presents a front view of the eye parts that are involved in forming a clear image of objects at near and far distances. What are structures 1 and 2?
Mammalian sense organs
The diagram illustrates several of the nerve pathways involved in a reflex action. If the pathway at X is damaged, how is the reflex affected?
Mammalian nervous system
Which of the following statements about hormones are true?
Mammalian hormones
The diagram illustrates the bones in the arm. Which label indicates the radius?
Specialised cells, tissues and organs
A study of reaction times used three comparable large groups of adults. In each case, the adult had to press a button as soon as a light flashed. The interval from the light switching on to the button being pressed was recorded. Group 1 carried out the task 30 minutes after smoking a cigarette. Group 2 carried out the task 30 minutes after drinking 2 units of alcohol. Group 3 acted as the control group. This control group did not smoke or drink alcohol. The graph presents the findings from this study. What is the best conclusion from the data?
Mammalian nervous system
What is one characteristic shared by all bacteria?
Features of organisms
Yeast is used in alcohol production. What is the other product formed in this process?
Anaerobic respiration
In a pyramid of biomass, the biomass of the producers is $800\,\text{g m}^{-2}$. What are the probable biomass values of the herbivores and the carnivores?
Energy flow
Which diagram shows the movement of carbon atoms through an ecosystem?
Nutrient cycles
An experiment designed to investigate osmosis is arranged as shown. What happens to the level of the liquid in tube X and the concentration of the salt solution?
Diffusion and osmosis
The diagram illustrates the nitrogen cycle. Which stages include bacteria?
Nutrient cycles
One way to control the malarial mosquito is to drain stagnant water. Which stages of the mosquito life cycle are affected by this method?
Asexual and sexual reproduction
Which gas is involved in causing acid rain?
Effects of humans on ecosystems
Which statement accurately describes the offspring produced through asexual reproduction?
Asexual and sexual reproduction
The graph illustrates how the dry mass of a seed alters as it germinates and develops. What causes the change shown between points S and T?
Respiration
The graph illustrates the blood concentration of three of the four hormones FSH, LH, oestrogen and progesterone during a menstrual cycle. Which hormone is not shown?
Sexual reproduction in humans
HIV infection can lead to death from AIDS. The graph illustrates AIDS-related deaths from 1990 to 2015 in a country. What is the most plausible explanation for the pattern in the number of AIDS-related deaths after 2005?
Disease
Several statements about chromosomes are given. 1. A chromosome contains one long DNA molecule. 2. Chromosomes contain genes. 3. During cell division, meiosis keeps the chromosome number unchanged. 4. The usual human chromosome number is 46. Which of these statements is correct?
Nuclear division
A single gene possesses two codominant alleles, $A^E$ and $A^F$, together with one recessive allele, $A^G$. How many distinct genotypes and phenotypes can occur?
Inheritance
What is one outcome of natural selection?
Selection
The diagrams illustrate an enzyme molecule and several substrate molecules. Which diagram represents the substrate molecule for this enzyme?
Enzyme action
State one advantage of genetic engineering.
Genetic modification
The graphs illustrate factors that influence the rate of photosynthesis. At which positions on the graphs might the rate of photosynthesis be restricted by light intensity?
Photosynthesis
The diagram illustrates how cells are organised within a green leaf. The brackets label different cell types. No cell contents are shown. Which types of cells have chloroplasts?
Leaf structure
Why are newly germinated seeds unable to develop into healthy plants when magnesium ions are absent?
Mineral nutrition
Milk is composed of water, carbohydrates, proteins, fats, and certain minerals and vitamins. The graph shows the outcome of an experiment. For 18 days, one group of young rats received $3\,\text{cm}^3$ of milk each day. On day 18, this group stopped receiving milk, whereas a second group of young rats was given milk. All other variables were kept the same for both groups of rats. What explains these results?
Diet
Which statement correctly describes chemical digestion in the human alimentary canal?
Human digestive system
Four cell features are shown below. 1 cell membrane 2 chloroplasts 3 nucleus 4 starch grains Which two of these features are present in animal cells?
Cell structure and function
Which two nutrients can result in deformed bones if the diet lacks either one?
Mineral nutrition
The diagram presents a cross-section of a plant stem. Which process causes substances to move in region Z?
Transpiration and translocation
What does transpiration mean?
Transpiration and translocation
In what ways do veins differ from arteries?
Blood vessels
Sickle cell anaemia is a genetic condition that leads to abnormal red blood cells. Which health problem will this change in the red blood cells cause?
Blood
The diagram illustrates the pressures on the left side of the heart during a single heartbeat. At the moment labelled X, which valves are open and which are closed?
Heart
What are some uses of energy released by respiration?
Respiration
Which statements concerning gaseous exchange in the alveoli are correct?
Human gas exchange
The graphs display a person's breathing measurements while at rest and while exercising. By how much does the breathing rate rise when the person moves from rest to exercise?
Human gas exchange
Which diagram illustrates the diffusion of substances between the blood and dialysis fluid during dialysis?
Excretion
Which one of the following statements about diffusion is correct?
Diffusion and osmosis
Following exercise, the human body temperature often increases above normal. What will help it return to normal?
Temperature control
The diagrams show the frontal view of the pupil and iris of the eye at different light intensities. Which row gives the correct description of diagram X?
Mammalian sense organs
The diagram illustrates several of the nerve pathways linked to a reflex action. If the pathway at X is damaged, what effect will this have on the reflex?
Mammalian nervous system
What takes place after insulin is injected?
Blood glucose control
The diagram presents the bones in the forelimb. Which bones make up the hinge joint of the forelimb?
Specialised cells, tissues and organs
In an experiment, one person measured their reaction time by recording how long it took to catch a ruler that was released by someone else. They then carried out the same test again some time after drinking alcohol. Which graph represents their results?
Mammalian nervous system
What is one characteristic shared by all bacteria?
Features of organisms
What is the principal function of yeast in the production of beers and wines?
Anaerobic respiration
What does the term food chain mean?
Energy flow
Why is it important for carbon to be cycled in nature?
Nutrient cycles
An experiment arranged as shown is used to study osmosis. What changes occur to the level of the liquid in tube X and to the concentration of the salt solution?
Diffusion and osmosis
The diagram illustrates part of the nitrogen cycle. Which processes are P, Q, R and S?
Nutrient cycles
Removing stagnant water is one way of controlling the mosquito that spreads malaria. Which parts of the mosquito life cycle are affected by this method?
Asexual and sexual reproduction
The table presents the source and the effect of four air pollutants. What are the four pollutants?
Effects of humans on ecosystems
The diagram shows the mass of DNA in cells that are dividing. Which row identifies this type of cell division?
Nuclear division
The graph illustrates how the dry mass of a seed changes as it germinates and develops. What causes the change shown between points S and T?
Photosynthesis
The graph illustrates the concentration in the blood of three of the four hormones FSH, LH, oestrogen and progesterone during a menstrual cycle. Which hormone is missing?
Sexual reproduction in humans
The table presents statements about HIV. Which row shows the statements correctly as true or false?
Disease
Can you give one example of discontinuous variation in humans?
Variation
A single gene has two codominant alleles, $A^{E}$ and $A^{F}$, together with one recessive allele, $A^{G}$. How many distinct genotypes and phenotypes can occur?
Inheritance
What is one outcome of natural selection?
Selection
Which statement concerning enzymes is invariably correct?
Enzyme action
As a nucleus divides by meiosis, alterations may occur that lead to a gamete with an unusual number of genes or chromosomes. Which alteration could lead to a gamete that may cause a child to have Down’s syndrome?
Nuclear division
The graphs illustrate factors that influence the rate of photosynthesis. At which points on the graphs might the rate of photosynthesis be restricted by carbon dioxide concentration?
Photosynthesis
The diagram illustrates how the cells are organised inside a green leaf. The brackets identify different cell types. No internal cell structures are shown. Which cell types contain chloroplasts?
Leaf structure
What is likely to happen to a plant if it does not obtain enough magnesium ions from the soil?
Mineral nutrition
The table displays the colours produced when three different foods are tested for carbohydrates, fats and proteins. Which nutrients are found in foods X, Y and Z?
Biological molecules
Which statement concerning chemical digestion in the human alimentary canal is correct?
Human digestive system
The diagram depicts the human lungs and the structures connected with them.
Human gas exchange
A farmer is cultivating a tomato crop.
Photosynthesis
A man is preparing food in a very hot kitchen, and sweat is being secreted by sweat glands in his skin.
Temperature control
The kapok tree is a flowering plant that grows very quickly until it becomes one of the tallest trees in a tropical rainforest ecosystem. Climbing plants twine around its stem, and the tree offers a habitat for insect-eating birds and frogs. Bats feed on nectar from its flowers and pollinate them, allowing the tree to make small, light seeds. Insects eat its leaves, and when the leaves drop to the ground they come into contact with soil bacteria and fungi.
Energy flow
This graph illustrates the way blood alcohol concentration varies after a person has drunk alcohol.
Absorption and assimilation
Explain the ‘lock and key’ hypothesis of enzyme action with a named example.
Enzyme action
Explain the part played by the nucleus and cell division in the inheritance of characteristics from parents to offspring.
Nuclear division
Water enters living organisms and is moved to all of their cells. Compare how water is transported in a human and in a flowering plant.
Uptake and transport of water and ions
Sperm cells and pollen grains both play a part in sexual reproduction. Compare the functions of a sperm cell and a pollen grain, and describe how the structure of each is adapted to its function.
Asexual and sexual reproduction
The diagram presents a photomicrograph of the lower side of a leaf.
Leaf structure
The diagram illustrates the circulatory system in a fish. Both human lungs and fish gills provide a large surface area for gas exchange.
Heart
The table gives the mass of each component present in $250\text{ cm}^3$ of cow’s milk.
Diet
The investigation looked at how likely pregnancy was after sexual intercourse on selected days within the menstrual cycle. The graph presents the findings from this investigation.
Sexual reproduction in humans
A few laundry detergents used for cleaning clothes include enzymes. Those enzymes digest the molecules responsible for stains.
Effects of temperature and pH
The diagram illustrates a cross-section of an insect-pollinated flower.
Sexual reproduction in plants
Costa Rica is a relatively small nation, occupying about $0.03\%$ of the Earth’s surface. Roughly $5\%$ of the planet’s plant and animal species are present in Costa Rica.
Effects of humans on ecosystems
Define what is meant by the term drug.
Disease
Outline why a seed must receive a plentiful supply of oxygen.
Aerobic respiration