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AQA Science © Nelson Thornes Ltd 2006 1 B3 1 Summary Exchange of materials Chapter review
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 2 How do substances move in and out of cells? Diffusion – passive movement of substances along a concentration gradient. Osmosis – movement of water along a concentration gradient through a partially permeable membrane. Active transport – movement of substances against a concentration gradient, or across a partially permeable membrane, using energy produced by respiration.
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 3 How are the lungs adapted for effective gas exchange? Breathing movements – good concentration gradient. Alveoli – massive surface area for diffusion. Moist surfaces so gases dissolve for efficient diffusion. Rich blood supply – so concentration gradient maintained. Short distance between alveoli and blood.
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 4 How is your gut adapted for the absorption of your food? Large food molecules broken down into small food molecules (digestion). Villi – large surface area for diffusion. Rich blood supply – maintains concentration gradient for diffusion. Short distances for diffusion. Moist surfaces. Active transport of substances.
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 5 What adaptations are needed for exchange of gas and solutes in any organism? A large surface area to give plenty of opportunity for substances to diffuse. A way of removing the substances exchanged (e.g. a rich blood supply) to maintain a steep concentration gradient and carry them to where they are needed. Moist surfaces for substances to dissolve. A short distance between the two areas – this makes diffusion as effective as possible.
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 6 How are plants adapted for exchange of substances? Leaves: flat and thin for large surface area and short diffusion distances; internal air spaces; stomata to let air in and out. Roots: many tiny roots and root hairs for large surface area; short diffusion distances; active transport to work against concentration gradients. Photo: John Kaprielian
B3 1 Summary AQA Science © Nelson Thornes Ltd 2006 7 What is transpiration and what factors affect it? Temperature. Light levels. Air movements. Carbon dioxide levels.
Exchange of materials Chapter review.
Diffusion is the process by which particles of gases or liquids spread out from an area where there are lots of them to areas where there are fewer of.
Name four factors that increase the rate of transpiration and explain why: What provides the following with a large surface area? Lungs: Small intestine:
B4 a-d Pig (F). Name the pores in the bottom of a leaf.
Exchange in plants Text p.228.
How can a shark find injured prey so quickly?
Topic 2 Organisms and Energy 1.Aerobic Respiration 2.Exercise 3.Anaerobic Respiration 4.Photosynthesis 5.Limiting factors 6.Water Transport.
B4 a-d Pig (H). What is the job of air spaces?
Why would enzymes have different optimums
Active transport p.216.
Movement in and out of cells
Gas exchange in Animals Internal (2.3). Gas exchange in animals All animals respire aerobically to release energy needed for cellular processes.
Keywords: alveoli, capillaries, oxygen, glucose, Keywords: lactic acid, exercise, muscles, energy, cramp B2 Topic 2 Organisms and Energy This topic looks.
Movement In and Out of Cells
How dissolved substances cross body surfaces. Body surfaceDissolved substances Small intestine, via villi, to blood. Alveoli to blood and vice versa.
Topic 2 Organisms and Energy
Outline for revision DIFFUSION, OSMOSIS, ACTIVE TRANSPORT.
Gas Exchange in Animals. Respiration All living things carry out respiration.
AS Level Biology Lesson 2. Gas exchange and respiration If cells are to stay active, grow and divide they need energy. This energy comes from the oxidation.
Let’s look at one example involving osmosis. Osmosis is the diffusion of water across a semi permeable membrane such as a cell membrane. A semi permeable.
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