Cambridge Practice · S1 Science SA2 Focus

🔋

Part 1

Aerobic Respiration

Word equation: glucose + oxygen → carbon dioxide + water (+ energy released). It happens in the mitochondria of every cell.

Breathe onto a cold mirror and it mists up; bubble your breath through limewater and it turns cloudy. What do these two results show?

2 marks

The two substances your body takes in when it respires

That your muscles have been working without enough oxygen

The two substances aerobic respiration makes

That unburnt food particles are leaving your lungs

Which gas is used up (a reactant) in aerobic respiration?

1 mark

In which part of the cell does aerobic respiration take place?

1 mark

Mitochondria

Cell membrane

Nucleus

Chloroplast

Muscle cells respire faster than most other cells, and contain many mitochondria. What is the best reason?

2 marks

Muscle cells are simply bigger than other cells

Muscle cells have no nucleus

Muscle cells store oxygen instead of using it

Muscle cells need a lot of energy to contract and move, so they respire more and need many mitochondria

Besides carbon dioxide and water, what does respiration release that the body needs for movement, growth and warmth?

1 mark

AEROBIC RESPIRATION — SECTION SCORE

0/7

🩸

Part 2

Blood

Four parts of blood: red blood cells (carry oxygen), white blood cells (fight infection), platelets (clotting), and plasma (the liquid that carries everything else).

Which type of blood cell carries oxygen around the body?

1 mark

Red blood cells

White blood cells

Platelets

Plasma

What is the name of the red protein in red blood cells that joins to oxygen?

1 mark

Red blood cells have no nucleus. Why is this an advantage?

2 marks

It makes them lighter so they float

It stops them fighting infection

There is more room inside for haemoglobin, so each cell can carry more oxygen

It lets them make their own DNA faster

When a person has an infection, the number of white blood cells rises quickly. Why?

1 mark

To carry more oxygen to the wound

To clot the blood and seal the cut

To engulf and destroy pathogens (germs) and make antibodies

To carry glucose to the muscles

Q10

Which part of the blood helps it to clot and seal a cut?

1 mark

Platelets

Red blood cells

Plasma only

Haemoglobin

Q11

What is the name of the liquid part of blood?

1 mark

Q12

Which substance is transported dissolved in the plasma?

1 mark

Solid mineral crystals

Glucose (dissolved food)

Whole bacteria cells

Bones

BLOOD — SECTION SCORE

0/8

🌬

Part 3

Diffusion

Diffusion = the movement of particles from a region of high concentration to a region of low concentration. This is how gases move in and out of the blood.

Q13

Which statement best describes diffusion?

1 mark

Particles moving from low concentration to high concentration

Particles moving from high concentration to low concentration until evenly spread

Particles being pumped by the heart

Particles stopping completely

Q14

In the lungs, oxygen moves from the air sacs into the blood. Why does it move in that direction?

2 marks

Oxygen always moves towards the heart

Oxygen is pushed by platelets

There is more oxygen in the blood than in the air sacs

There is a higher concentration of oxygen in the air sacs than in the blood, so it diffuses into the blood

Q15

At the same time, carbon dioxide moves from the blood into the air sacs to be breathed out. Why?

1 mark

Carbon dioxide is heavier than oxygen

There is more carbon dioxide in the blood than in the air sacs, so it diffuses out

The lungs suck it out using muscles

Red blood cells carry it on haemoglobin only

DIFFUSION — SECTION SCORE

0/4

—

Respiration
& Blood

📺 Watch & Learn first

Aerobic Respiration

Blood

Diffusion

Respiration& Blood

📺 Watch & Learn first

Aerobic Respiration

Blood

Diffusion

Respiration
& Blood