Oct/Nov 2019

In a lesson on animal and plant cells, a student reads several statements about cell structure. Exactly three of the statements are correct. Which three statements are correct?

Cell structure and function

The table compares the absorption rates of two sugars, arabinose and glucose, in living and dead intestines. In every case, the sugar concentrations inside the intestines were identical. What are the main methods by which arabinose and glucose are absorbed in living intestine?

Absorption and assimilation

Why is the large surface area of a plant’s root hairs important?

Uptake and transport of water and ions

What is the principal reason for water rising to the leaves in xylem vessels?

Transpiration and translocation

What does double circulation mean?

Circulatory system

The diagram displays a cross-section of a vessel transporting oxygenated blood, viewed under a microscope. What vessel is this?

Blood vessels

Hypoplastic left heart failure is a rare cardiac condition in which the lower left chamber of the heart has developed abnormally and is far smaller than usual. The immediate effect of this condition is reduced blood flow to which blood vessel?

Heart

While an athlete is racing, the muscles in the legs need more energy than aerobic respiration can provide. Which substance accumulates in the leg muscles and leads to pain?

Anaerobic respiration

What takes place during expiration?

Human gas exchange

The pie charts illustrate the proportions of gases in samples of inspired air and expired air. Which segments are for which gases?

Human gas exchange

Inside a kidney dialysis machine, which substance is unable to diffuse through the dialysis membrane?

Excretion

Which statement is true in every case for both diffusion and osmosis?

Diffusion and osmosis

The diagram shows a cross-section of the skin. Which row identifies the functions of the labelled parts?

Specialised cells, tissues and organs

Which part of the brain detects changes in the blood concentration?

Homeostasis

The diagram depicts a cross-section of a human eye. In which part are the receptors for the pupil (iris) reflex located?

Mammalian sense organs

Which flow diagram illustrates the regulation of blood sugar levels?

Blood glucose control

At which end does a bone make a ball and socket joint, and at the other end a hinge joint?

Specialised cells, tissues and organs

Which risk is significantly raised by the nicotine present in cigarette smoke?

Disease

As cheese is produced, the pH of milk decreases and this makes the milk proteins coagulate. What is the principal reason for the pH becoming lower?

Anaerobic respiration

What type of organism makes penicillin, and what kind of infection can penicillin be used to treat?

Antibiotics

Four students are investigating a pond ecosystem on a clear sunny day. They notice that the underwater plants are releasing bubbles. What accounts for this observation?

Photosynthesis

The diagram illustrates a food web. In this web, what is meant by a food chain?

Energy flow

Which process takes place by active transport?

Active transport

Certain bacteria function most successfully in waterlogged soils, where they can gain oxygen for respiration by breaking down nitrates. Nitrogen gas is then given off as a waste product. To which type of bacteria does this description refer?

Nutrient cycles

How many blood meals on human blood must an uninfected mosquito take in order to pass the malarial parasite on to people?

Disease

Sewage is discharged into a river. Which curve shows the oxygen concentration in the river?

Effects of humans on ecosystems

The diagram illustrates the formation of a pollen tube and how it enters the ovule. Which structure becomes the testa after fertilisation?

Sexual reproduction in plants

The diagram illustrates the life cycle of a plant species. During which stage does meiosis (reduction division) take place?

Sexual reproduction in plants

The graph illustrates how hormone concentrations vary over the course of a menstrual cycle. Which curve shows progesterone?

Sexual reproduction in humans

The diagram shows gametes P and Q joining together to form cell R. Cell R then forms gametes S, T, U and V. Which statement about the chromosome numbers in the cells and gametes is correct?

Nuclear division

Which of the following statements about DNA are correct?

DNA

Which of the following is not an advantage of genetic engineering?

Genetic modification

The father’s blood group is AB and the mother’s blood group is O. What ratio of blood groups is expected among the offspring?

Inheritance

Which of these statements about enzymes is correct?

Enzyme action

Which statement concerning dominant and recessive alleles is false?

Inheritance

Which diagram shows substances entering and leaving a leaf while glucose is being made?

Photosynthesis

A small mountain lake contains aquatic plants growing below the water on the lake bed. Soon after heavy rainfall, the mud on the lake bed is stirred up and the water level rises. Why does this make the rate of photosynthesis in these plants decrease?

Photosynthesis

The elements named below occur in every living organism. Which element do plants not take in from the soil?

Mineral nutrition

The table gives details of some characteristics of four people. Which person needs the greatest energy intake in their diet?

Diet

In which part of the body do both the physical and chemical breakdown of food take place?

Human digestive system

A human cheek cell and a spongy mesophyll cell from a leaf are viewed through a microscope. Which structures are visible in both cells?

Cell structure and function

The table gives the absorption rates of two different sugars, arabinose and glucose, in living and dead intestines. In each case, the sugar concentrations inside the intestines were identical. What are the main methods by which arabinose and glucose are absorbed in living intestine?

Absorption and assimilation

Which statements concerning root hairs are correct?

Specialised cells, tissues and organs

What is the primary reason for water being transported up to the leaves in xylem vessels?

Transpiration and translocation

After a protein-rich meal, which blood vessel will contain the highest concentration of urea?

Excretion

In what way is blood flow through the lungs different from blood flow through the rest of the body?

Circulatory system

Which of the following statements about blood vessels is correct?

Blood vessels

Which equation shows anaerobic respiration in humans?

Anaerobic respiration

Which process does not use the energy that respiration releases?

Diffusion and osmosis

The pie charts illustrate the proportions of gases in samples of inspired and expired air. Which segments correspond to which gases?

Human gas exchange

In a kidney dialysis machine, which substance is unable to diffuse across the dialysis membrane?

Urinary system

Which of the following statements about active transport in root hair cells are correct?

Active transport

On a hot day, the cheeks of a light-skinned person may look red. What causes this?

Temperature control

Which part of the brain senses alterations in blood concentration?

Homeostasis

The diagram displays a cross-section of the skin. Which structures become active when a person feels cold?

Temperature control

Under which condition would the quantity of insulin released into a person’s blood be greatest?

Blood glucose control

The diagram illustrates the bones in the area of the right shoulder. What is bone M?

Specialised cells, tissues and organs

Which risk is significantly raised by the nicotine found in cigarette smoke?

Heart

Which organisms in this list count as microorganisms?

Concept and use of a classification system

What kind of organism makes penicillin, and what kind of infection can be treated with penicillin?

Antibiotics

Why is the flow of energy in an ecosystem regarded as non-cyclic?

Energy flow

Each square metre of grassland receives $1\,004\,000\,\text{kJ}$ of sunlight energy per year. The table illustrates how this energy is used. How much of the $1\,004\,000\,\text{kJ}$ of sunlight energy was used by the grass plants?

Energy flow

Discs of uncooked potato tissue are first weighed to find their initial mass. They are then left in sucrose solutions with different concentrations. After 1 hour, they are weighed again to obtain their final mass. The graph shows how the ratio of initial mass to final mass varies with sucrose solution concentration. Which concentration of sucrose solution has the same water potential as the cells in the potato discs?

Diffusion and osmosis

Certain bacteria are most successful in waterlogged soils, where they can get oxygen for respiration by breaking down nitrates. Nitrogen gas is given off as a waste product. To which type of bacteria does this description apply?

Nutrient cycles

How many times does an uninfected mosquito need to feed on human blood in order to pass the malarial parasite through the human population?

Disease

The diagram illustrates the sources of a pollutant type that enters an ocean bay. What identifies the pollutant type?

Effects of humans on ecosystems

Which structure houses the ovary in a flowering plant?

Sexual reproduction in plants

The diagram illustrates the life cycle of a plant species. At what stage does meiosis (reduction division) take place?

Nuclear division

The diagram illustrates the female reproductive system. In which part does implantation take place?

Sexual reproduction in humans

When controlling female fertility, which hormones may be used to prevent ovulation, and which may be used to promote ovulation?

Mammalian hormones

A student made some comments about chromosomes, but several are inaccurate. 1. A human body cell contains $46$ pairs of chromosomes. 2. In gametes, chromosomes occur in pairs. 3. Males have one X chromosome and one Y chromosome in every body cell. 4. Chromosomes consist of a long DNA molecule that is split into regions called genes. 5. Chromosomes contain genes that are divided into regions called DNA molecules. Which two statements are correct?

DNA

Poachers hunt elephants for their tusks, because tusks provide ivory. In $1930$, at a National Park, $1\%$ of the elephants were born with no tusks. The absence of tusks was caused by a gene mutation. At present, in the same area, $15\%$ of the females and $9\%$ of the males are tuskless. Which statements could account for this rise in the number of tuskless elephants?

Selection

The diagram illustrates a family tree showing the inheritance of night-blindness. What is the probability that the unborn child, $9$, will be a male affected by night-blindness?

Inheritance

What occurs to an enzyme after it has catalysed a reaction?

Enzyme action

Which of the following statements about dominant and recessive alleles is not correct?

Inheritance

Some chemical symbols are shown. What equation represents photosynthesis?

Photosynthesis

The diagram illustrates some of the structures visible in a transverse section of a dicotyledonous leaf. Which two features are absent from this diagram?

Leaf structure

The elements named below occur in all living organisms. Which one is not taken up by plants from the soil?

Mineral nutrition

The table shows several characteristics of four individuals. Which person needs the greatest energy intake in their diet?

Diet

Which structure contains villi that increase its surface area?

Absorption and assimilation

The table sets out some of the components present in $100\,\text{cm}^3$ of cow’s milk, breast milk and breast milk substitute (formula milk).

Diet

The diagram illustrates the layout of a virus.

Cell structure and function

The graph plots the water-loss rates of three plants, D, E and F, over the first 14 minutes of an experiment. These plants are from different species, but they are all grown under identical conditions.

Transpiration and translocation

Draw a genetic diagram to show how two parents who find Brussels sprouts bitter can have a child who does not find Brussels sprouts bitter.

Inheritance

The diagrams illustrate a model that is used to show the process of human breathing.

Human gas exchange

The pictures depict a man who is fishing.

Mammalian nervous system

Explain how energy originating from the Sun may ultimately be used in active transport within the alimentary canal.

Energy flow

Describe and explain the way in which a protein molecule eaten in food is changed into urea and then removed from the body.

Excretion

Describe and explain the route by which a nitrate ion in the soil becomes part of a storage molecule in a plant seed.

Mineral nutrition

This flowering plant species has two flower forms. Some plants bear flowers known as pin, while others bear flowers known as thrum. The diagrams show cross-sections through parts of these two flower forms.

Inheritance

Plants take in light energy for the process of photosynthesis.

Genetic modification

Syphilis is an infectious illness spread through sexual contact. A person’s blood can be checked for antibodies that are made after infection by the pathogen responsible for syphilis.

Disease

Proteins form a key part of the human diet. After protein molecules are digested, the digestion products are taken into the blood.

Absorption and assimilation

The statements E to L concern the process of cell division.

Nuclear division

The diagrams depict two kinds of cell that are adapted for specific functions.

Specialised cells, tissues and organs

Respiration in human muscle cells can happen both when oxygen is present and when oxygen is absent.

Aerobic respiration

Describe the ways in which human activity may damage the ecosystem of a tropical rainforest.

Effects of humans on ecosystems

After sexual intercourse in humans, fertilisation can happen.

Sexual reproduction in humans