Biology

What is the basic building block of all living things?

• AThe atom
• BThe organ
• CThe cell✓
• DThe molecule

Answer: Cells are the smallest unit of life; all living organisms are made of one or more cells.

Which part of a plant cell carries out photosynthesis?

• ACell membrane
• BChloroplast✓
• CCell nucleus
• DLarge vacuole

Answer: Chloroplasts contain chlorophyll, which traps light energy for photosynthesis.

Which gas do plants take in for photosynthesis?

• ANitrogen
• BOxygen from the air
• CCarbon dioxide✓
• DHydrogen from the air

Answer: Plants absorb carbon dioxide and release oxygen during photosynthesis.

Which organ pumps blood around the body?

• AHeart✓
• BLiver
• CLungs
• DKidney

Answer: The heart is a muscular organ that pumps blood through the circulatory system.

In a food chain, the arrows show:

• AThe order the animals were born in
• BWho eats who, pointing to the eater✓
• CThe direction the animals walk in each day
• DWhich animal is biggest

Answer: Food-chain arrows point in the direction energy flows — towards the organism doing the eating.

What do we call animals that eat only plants?

• APredators
• BHerbivores✓
• CCarnivores
• DOmnivores

Answer: Herbivores eat only plants; carnivores eat meat; omnivores eat both.

Which system in the body includes the lungs and is used for breathing?

• ASkeletal system
• BRespiratory system✓
• CDigestive system
• DNervous system

Answer: The respiratory system (lungs, trachea, etc.) takes in oxygen and removes carbon dioxide.

What is the job of the skeleton?

• ATo pump blood round the body
• BTo break down food in the stomach
• CTo carry messages to and from the brain
• DTo support and protect the body✓

Answer: The skeleton supports the body, protects organs, and allows movement with muscles.

Which of these is a healthy way to keep the heart strong?

• AEating sweets
• BNever moving
• CSmoking
• DRegular exercise✓

Answer: Regular exercise strengthens the heart muscle and improves circulation.

During reproduction in mammals, the male sex cell is the:

• ASeed
• BSperm✓
• CEgg
• DWomb

Answer: In mammals the male gamete (sex cell) is the sperm; the female gamete is the egg.

Bacteria that cause disease are sometimes called:

• AMinerals
• BNutrients
• CCells
• DPathogens✓

Answer: A pathogen is a microorganism (such as some bacteria or viruses) that causes disease.

A balanced diet should include a variety of:

• AJust carbohydrates
• BSugary food and drink alone
• CFats and oils on their own
• DFood groups including protein, carbohydrate, fat, vitamins and minerals✓

Answer: A balanced diet contains the right amounts of all the main food groups.

Which of these best describes a 'habitat'?

• AThe place where an organism lives✓
• BA group of animals of the same kind
• CThe weather in an area over a year
• DA type of animal food

Answer: A habitat is the natural home or environment of a plant or animal.

Which structure is found in plant cells but is absent from animal cells?

• ACell membrane
• BMitochondria
• CCell wall✓
• DNucleus

Answer: A cell wall made of cellulose surrounds every plant cell and gives it support and a fixed shape. A membrane, mitochondria and a nucleus are all present in animal cells too.

A mature red blood cell has no nucleus. How does this help it do its job?

• AIt protects the cell from attack by bacteria
• BIt lets the cell divide much faster
• CIt allows the cell to make its own food
• DIt leaves more room for haemoglobin✓

Answer: Losing the nucleus frees up space inside the cell for haemoglobin, the red pigment that binds oxygen in the lungs and releases it in the tissues, so each cell can carry more oxygen.

A root hair cell has a long, thin extension that pushes out into the soil. How does this help the plant?

• AIt stores starch for the winter
• BIt carries sugars up to the leaves
• CIt anchors the plant against the wind
• DIt gives a large surface area for absorbing water✓

Answer: The extension greatly increases the surface area in contact with the soil, so water and mineral ions are taken up much more quickly. Sugars are carried by phloem tissue, not by root hairs.

Which word equation describes photosynthesis?

• Aglucose + oxygen → carbon dioxide + water
• Bcarbon dioxide + water → glucose + oxygen✓
• Coxygen + water → glucose + carbon dioxide
• Dglucose + carbon dioxide → oxygen + water

Answer: Photosynthesis uses light energy trapped by chlorophyll to build glucose from carbon dioxide and water, giving off oxygen as a waste product. Turning that equation round describes respiration instead.

Which word equation describes aerobic respiration?

• Acarbon dioxide + water → glucose + oxygen
• Bglucose → lactic acid + energy
• Coxygen + carbon dioxide → glucose + water
• Dglucose + oxygen → carbon dioxide + water✓

Answer: Aerobic respiration releases energy by combining glucose with oxygen, producing carbon dioxide and water. Breaking glucose down into lactic acid is anaerobic respiration, which happens when oxygen runs short.

The enzyme amylase is found in saliva. Which food group does it begin to break down?

• AFat
• BProtein
• CStarch✓
• DFibre

Answer: Amylase is a carbohydrase, so it breaks starch down into smaller sugars. Protein is digested by protease and fat by lipase, while fibre passes through undigested.

In which organ does the digestion of protein begin?

• AThe mouth
• BThe small intestine
• CThe stomach✓
• DThe liver

Answer: The stomach releases protease enzymes together with hydrochloric acid, and those acidic conditions are exactly what the protease needs to start breaking protein down.

The lining of the small intestine is covered in millions of tiny villi. What is their main purpose?

• ATo produce bile for digesting fat
• BTo increase the surface area for absorption✓
• CTo push food along by muscular contractions
• DTo kill any bacteria in the food

Answer: Villi are finger-like projections that give the intestine wall an enormous surface area, so digested nutrients pass into the blood far more quickly. Bile is made in the liver.

What happens to the diaphragm and the ribcage when you breathe in?

• AThe diaphragm contracts and flattens and the ribcage moves up and out✓
• BThe diaphragm relaxes and domes upwards and the ribcage drops
• CBoth the diaphragm and the ribcage stay completely still
• DThe diaphragm contracts and the ribcage moves down and in

Answer: Breathing in is an active movement: the diaphragm contracts and flattens while the ribs are pulled upwards and outwards. That increases the volume of the chest and lowers the pressure inside it, so air flows in.

In the alveoli of the lungs, which way do the gases move?

• AOxygen and carbon dioxide both move into the blood
• BOxygen and carbon dioxide both move into the air
• CCarbon dioxide moves into the blood and oxygen into the air
• DOxygen moves into the blood and carbon dioxide into the air✓

Answer: Each gas diffuses from where it is more concentrated to where it is less concentrated, so oxygen passes from the air in the alveoli into the blood while carbon dioxide passes the other way.

Which of these is an example of variation caused entirely by the environment?

• AEye colour
• BBlood group
• CA scar from an accident✓
• DNatural hair colour

Answer: A scar is the result of an injury during a person's lifetime, so it cannot be passed on to their children. Eye colour, blood group and natural hair colour are all decided by genes.

Human height is described as continuous variation. What does that mean?

• AIt is controlled by one single gene
• BIt falls into a few separate groups
• CIt can take any value within a range✓
• DIt is decided only by what you eat

Answer: Continuous variation gives a smooth range of values with no gaps, so height can be any measurement between the extremes. Characteristics that fall into distinct categories, such as blood group, show discontinuous variation.

Where in a cell are the chromosomes that carry a person's genes found?

• AIn the cytoplasm
• BIn the cell membrane
• CIn the mitochondria
• DIn the nucleus✓

Answer: Chromosomes are long, coiled molecules of DNA held inside the nucleus, and a gene is a section of a chromosome that codes for one characteristic.

In the food chain grass → rabbit → fox, what do the arrows show?

• AThe direction in which energy is transferred✓
• BWhich animal is the largest
• CThe order in which the species evolved
• DThe direction in which the animals move

Answer: An arrow in a food chain always points from the organism being eaten towards the one eating it, because it shows the direction in which energy and biomass are passed on.

A disease sharply reduces the number of foxes in a woodland. What is the most likely immediate effect on the rabbits the foxes eat?

• AThe rabbit population falls
• BThe rabbit population rises✓
• CThe rabbit population stays exactly the same
• DThe rabbits start to eat meat instead

Answer: With fewer predators, fewer rabbits are eaten, so their numbers rise until food supply or disease begins to limit them. This is what interdependence means: a change in one species affects the others in the web.