Feb/March 2025

The diagram illustrates several processes performed by living organisms. Which two characteristics of living organisms are shown by arrows P and Q?

Characteristics of living organisms

Enzyme R breaks down protein in the stomach. Four test-tubes are prepared, and each one contains equal amounts of protein and enzyme R. The test-tubes are maintained at different pH values and temperatures. In which test-tube will protein digestion happen fastest?

Enzymes

A student studied the rate of photosynthesis in four plant species at $20\,^{\circ}\mathrm{C}$ and at $30\,^{\circ}\mathrm{C}$. Every other condition was kept unchanged. Which statement is a valid conclusion drawn from these data?

Photosynthesis

At which stage of nutrition do food molecules become incorporated into a body cell?

Absorption

The diagram shows the human teeth in the mouth. Which kinds of teeth are used to grind food?

Physical digestion

What functions does the hydrochloric acid in gastric juice perform?

Chemical digestion

In which part of the body does most absorption of nutrients take place?

Absorption

Which statement explains a function of xylem in a plant stem?

Xylem and phloem

Which row lists the parts of the human circulatory system?

Circulatory systems

What is one function of white blood cells?

Blood

Which substances function as body defences?

Diseases and immunity

A domesticated llama is given the scientific name $\text{Lama glama}$. A domesticated sheep is given the scientific name $\text{Ovis aries}$. What is the genus name of the llama and the species name of the sheep?

Concept and uses of classification systems

A student studies how physical activity affects their breathing rate. They measure their breathing rate at different times. Which row shows the change in the student’s breathing rate?

Gas exchange in humans

Which gas is required for aerobic respiration?

Aerobic respiration

During anaerobic respiration in yeast, which substance is formed?

Anaerobic respiration

In which part of the human body is urea removed?

Excretion in humans

What path does an electrical impulse follow in a simple reflex arc?

Coordination and response

What function does the iris have?

Sense organs

Tropic responses may be either positive or negative. If a plant grows towards the stimulus, the response is positive (+). If a plant grows away from the stimulus, the response is negative (-). The diagram shows a plant showing tropic responses. Which row gives the tropic responses at position M and at position N?

Tropic responses

Several plants are formed by asexual reproduction. Which statement about these plants is true?

Asexual reproduction

During pollination, pollen is transferred from which structure to which structure?

Sexual reproduction in plants

Besides a suitable temperature, what other condition is always needed for seed germination?

Sexual reproduction in plants

The photograph depicts an arthropod, $\textit{Formica fusca}$. What is the reason for assigning $\textit{Formica fusca}$ to the correct group?

Features of organisms

What changes occur in the lining of the human uterus during the days leading up to the release of an egg cell?

Sexual reproduction in humans

Which term refers to a length of DNA that codes for a protein?

Chromosomes, genes and proteins

Polydactyly is an inherited condition that can occur in cats. It causes the affected offspring to have extra toes. The allele for polydactyly is dominant and is shown by the letter T. The allele for not having polydactyly is recessive and is shown by the letter t. A cat with genotype Tt is bred with a cat with genotype tt. What is the chance of the offspring having polydactyly?

Monohybrid inheritance

A student recorded the heights of her friends to investigate how they differ. Which statements are true for this kind of variation?

Variation

The diagram illustrates a food web. At which trophic levels does the leopard feed?

Food chains and food webs

Pythons were introduced by accident to a region during the 1990s. After that, they bred in the wild and turned into a pest. The number of pythons taken out of the wild can be used as an indication of population size, as shown. Which phase of the population growth curve of pythons is shown in 2005?

Populations

Which statement identifies a disadvantage of cultivating crop plants as a monoculture?

Food supply

What environmental impacts does deforestation have?

Habitat destruction

Which statement concerning non-biodegradable plastics in aquatic environments is correct?

Pollution

Which conservation methods are employed to safeguard endangered species?

Conservation

The photomicrograph displays a section of an animal cell. What structure is labelled X?

Cell structure

For what reasons are bacteria useful in biotechnology and genetic modification?

Biotechnology and genetic modification

In a green leaf, where are carbohydrates produced?

Photosynthesis

Which formula is used to work out the magnification of specimens?

Size of specimens

What raises the rate at which oxygen diffuses into a cell?

Diffusion

The apparatus illustrated is used to show osmosis. At the beginning of the demonstration, the mass of the dialysis tubing and its contents was 11.2 g, and by the end it was 9.4 g. Which solutions would produce this change in mass?

Osmosis

A student put amylase and starch solution into a test-tube. After a few minutes, the student tested samples of the liquid from the test-tube. They noted the colours of the samples after testing for starch and reducing sugar. Which row shows the test used and the expected results?

Enzymes

The evolutionary relationships among four bacterial species, P, Q, R and S, were compared. • Species P and Q share a more recent common ancestor than either one does with species R. • Species S evolved recently from species P. Which species has DNA base sequences that are least similar to those of the other three bacterial species?

Concept and uses of classification systems

The graphs illustrate how a plant’s rate of photosynthesis and rate of respiration varied during a $24$-hour period. Which graph shows the correct rate of photosynthesis and rate of respiration?

Photosynthesis

The photomicrograph depicts a section of the underside of a leaf. What structure is indicated by X?

Leaf structure

A student is informed that their diet is not balanced and that they may be at risk of developing scurvy. What should the student do to lower their risk of scurvy?

Diet

The diagram illustrates the four kinds of human tooth. Which teeth are used to grind food?

Physical digestion

Which substance is responsible for the change in pH as food enters the small intestine?

Digestive system

Under which conditions does transpiration happen at the greatest rate?

Transpiration

The diagram illustrates a heart defect that some babies are born with. The arrows show the direction in which blood flows. Which statement explains why this heart defect could lead to poor growth in the baby?

Heart

The diagram illustrates how vaccination affects the human body. Three parts in the diagram are labelled with numbers. Which of these parts are memory cells?

Diseases and immunity

Which structure prevents the trachea from collapsing during breathing?

Gas exchange in humans

Yeast is able to respire aerobically and anaerobically. For each molecule of glucose that yeast uses, how many additional molecules of carbon dioxide gas are released by aerobic respiration than by anaerobic respiration?

Aerobic respiration

The diagram depicts an arthropod. Which group is it classified in?

Concept and uses of classification systems

For a healthy human, which blood vessel contains the smallest concentration of urea?

Excretion in humans

A particular eye disorder can lead to the ciliary muscles staying permanently contracted. Which row shows the correct features for an eye with this disorder when compared with an eye that does not have it?

Sense organs

The liver and the pancreas act together to regulate the concentration of glucose in the blood. Which statement is correct?

Hormones

When it is dark, why do plant shoots grow upward while roots grow downward?

Tropic responses

Why should antibiotics be used only when they are necessary?

Drugs

Which row gives the description of self-pollination?

Sexual reproduction in plants

The list contains terms used to describe sexual reproduction. Which of these terms is used only to describe sexual reproduction in plants?

Sexual reproduction in plants

Which statement gives the correct description of the effect of a hormone in a 28-day human menstrual cycle?

Sex hormones in humans

Which hormone is chiefly responsible for the development of male secondary sexual characteristics?

Sex hormones in humans

What term describes a length of DNA that codes for a protein?

Chromosomes, genes and proteins

Which structures occur in both plant cells and bacterial cells?

Cell structure

Which of the following statements about the sex chromosomes is correct?

Chromosomes, genes and proteins

The graph illustrates the way the mass of DNA varies during mitotic cell division. At which point on the graph are two cells produced?

Mitosis

A man with blood group A and genotype $I^{A}I^{O}$ has a child with a woman who has blood group B and genotype $I^{B}I^{O}$. What is the probability that the child will have blood group O?

Monohybrid inheritance

What causes genetic variation within populations?

Variation

This food chain illustrates the transfer of energy to a human. lettuce $\rightarrow$ snails $\rightarrow$ duck $\rightarrow$ human From where did the lettuce get its energy?

Photosynthesis

The processes shown influence the concentration of carbon dioxide in the atmosphere. Which processes cause the concentration of carbon dioxide in the atmosphere to rise?

Nutrient cycles

Which organisms may serve as energy sources for decomposers?

Food chains and food webs

A coral reef includes species such as stony corals, sponges, seahorses and whale sharks. These species interact with one another and are influenced by the water temperature, salt concentration and oxygen concentration. Using all the information provided, what is being described?

Energy flow

Which factors could lead to a rise in the size of a rabbit population?

Populations

In what way does eutrophication cause fish to die?

Nutrient cycles

A cell measures $65\,\mu\text{m}$ across. What is this measurement in $\text{mm}$?

Size of specimens

The diagram illustrates a bacterial cell. Which cell structure allows bacteria to be useful in genetic modification?

Genetic modification

The diagram illustrates four mesophyll cells, W, X, Y and Z. Water passes through these cells. Which arrow indicates the direction in which water moves through these cells?

Transpiration

Three processes are given below. 1 Molecules or ions cross membranes. 2 Molecules or ions are transported using protein carriers. 3 Ions enter root hairs. Which of these processes can use active transport?

Active transport

A segment of a chromosome has $4500$ bases. It includes $1450$ G bases. What is the number of A bases present?

Chromosomes, genes and proteins

Which chemical element is present in proteins but not in carbohydrates?

Biological molecules

Which statement gives a description of enzymes?

Enzymes

Complete the sentences to describe enzymes. Choose words or phrases from the list. Each word or phrase can be used once, more than once, or not at all. amino acids, calcium, carbon, fatty acids, hydrogen, iron, magnesium, molecules, nitrogen, oxygen, water Enzymes are proteins. All proteins are built from a chain of smaller [BLANK] called [BLANK]. All proteins contain the chemical elements [BLANK], [BLANK], [BLANK] and [BLANK].

Enzymes

The human digestive system consists of the alimentary canal and the associated organs. Food passes along the alimentary canal, but it does not pass through the associated organs. One of the associated organs is the pancreas. State the letter in Fig. 2.1 that shows the pancreas and state the names of two enzymes released by the pancreas.

Digestive system

On Fig. 3.1, add a label line and the letter X to show the muscular wall of the left ventricle.

Heart

The Mexican hat plant shown in Fig. 4.1 is reproducing. Tick (✓) three statements that describe the reproduction shown in Fig. 4.1. Gametes are made. Implantation happens. There is only one parent involved. Pollination takes place before the stage shown in Fig. 4.1. The offspring are genetically identical to one another. This reproduction is asexual.

Sexual reproduction in plants

State one visible feature in Fig. 5.1 that shows this leaf insect is an insect.

Adaptive features

Barley is cultivated as a crop plant.

Selection

Fig. 1.1 illustrates particles moving through an epithelial cell in the small intestine.

Diffusion

A person's internal body temperature was measured, and the findings are shown in Fig. 2.1.

Homeostasis

Fig. 3.1 illustrates the percentage of water found in the different structures of the human body.

Genetic modification

Fig. 4.1 shows a section of a human placenta together with the umbilical cord. The arrows indicate the direction in which blood flows.

Sexual reproduction in humans

Fig. 5.1 illustrates a cross-section through a leaf.

Leaf structure

Microplastics are plastic fragments with a diameter of less than 0.5 cm. Fig. 6.1 shows the mass of microplastics in the oceans from 2000 to 2040.

Conservation