Topic 8 : Exchange and Transport in Animals Flashcards
Why do organisms need to transport substances in and out?
A: To supply cells with oxygen and nutrients
What substances need to be exchanged in organisms?
Oxygen and Carbon Dioxide
Why do multicellular organisms need exchange surfaces?
They have a low surface area to volume ratio so substances can’t diffuse efficiently into all cells.
What does surface area to volume ratio affect?
The rate at which substances can diffuse into or out of cells.
How are alveoli adapted for gas exchange?
They have a large surface area, thin walls (one cell tick), moist, good blood supply
What happens in the alveoli?
Oxygen diffuses into the blood and carbon dioxide diffuses out into the air.
What three factors affect the rate of diffusion?
Surface area, concentration gradient, and diffusion distance.
What is Fick’s Law for diffusion?
Rate of diffusion ∝ (surface area × concentration difference) ÷ membrane thickness.
How are red blood cells adapted for their function?
They have no nucleus, a biconcave shape, and contain haemoglobin to carry oxygen.
What is the role of white blood cells?
Phagocytes engulf pathogens; lymphocytes make antibodies.
What is the function of plasma in blood?
It carries dissolved substances like glucose
What is the function of platelets?
They help blood clot at wounds.
How are arteries adapted for their function?
Thick muscular walls and elastic fibres to cope with high pressure.
How are veins adapted for their function?
Thin walls, large lumen, and valves to prevent backflow of blood.
How are capillaries adapted for their function?
Very thin walls (one cell thick) for easy diffusion of gases and nutrients.
What is the function of the heart?
To pump blood around the body, delivering oxygen and removing waste.
Why are the walls of the left ventricle thicker than the right?
It pumps blood around the whole body, needing more force.
What is the role of valves in the heart?
They prevent backflow of blood.
What is aerobic respiration?
The release of energy from glucose using oxygen, producing carbon dioxide and water.
What is anaerobic respiration?
The release of energy without oxygen, producing lactic acid in animals.
How is anaerobic respiration different to aerobic?
It releases less energy and does not produce carbon dioxide or water.
What is the word equation for aerobic respiration?
Glucose + oxygen → carbon dioxide + water.
What is the word equation for anaerobic respiration in animals?
Glucose → lactic acid.
What is the equation for cardiac output?
Cardiac output = stroke volume × heart rate.
