T1 PP (PMT

ASK: 6,9, 11

(7) + (3)

(3)

• water has uneven distribution of charge and therefore a dipole

• *so it forms hydrogen bonds with other molecules*

• therefore lots of thermal energy is required to break these bonds

• water is a solvent = water molecules surround the ions/polar molecules and hydrogen bonds are formed between the dolute molecules and h20 molecules

Cohesion:

• Biological Importance:

  • Transpiration stream in plants: Cohesion allows water molecules to stick together and move as a continuous column through the xylem, from roots to leaves.

  • Helps maintain a constant flow of water, enabling transport of nutrients.

Adhesion:

• Definition: The attraction between water molecules and other polar surfaces (like xylem walls).

• Biological Importance:

  • Aids capillary action, helping water rise up narrow tubes like xylem vessels.

  • Helps counteract the force of gravity in tall plants.

High Latent Heat of Vaporisation

• Definition: The amount of energy needed to convert 1 gram of water from liquid to gas without a temperature change.

• Biological Importance:

  • Thermoregulation in organisms:

    • In humans, sweating is an effective cooling mechanism. As sweat evaporates, it absorbs a lot of heat energy from the body, cooling it down.

    • In plants, water evaporation from leaves (transpiration) cools the plant, preventing overheating.

  • Allows organisms to maintain a stable internal temperature — essential for enzyme function and metabolic processes.

(8) + (2)

(1)

• suitable substance eg. oxygen/glucose to body cells but also removal of CO2/waste from body

• SA:vol ratio to small = so distance for diffusion is larger

How does the heart affect the concentration gradient of solutes?

• The heart pumps blood around the body, maintaining a constant flow.

• This delivers solutes like oxygen and glucose to tissues and removes waste products.

• Continuous circulation prevents equilibrium and maintains steep concentration gradients for efficient diffusion between blood and cells.

Many foods are labelled in kilocalories (kcal). One calorie is equal to 4.18 joules. Which of the following is the average energy requirements for girls aged 13 in kilocalories (kcal)?

2223 kcal

what will happen to the additional energy if an individual takes in more energy than is required? (1)

State a time from the graph when the sound of an atrioventricular valve closing would be detected.

0.19s/0.91

Explain why the atrioventricular valves need to close. (2)

Which structures will fill with blood as a result of atrial systole? (1)

R & S