Separate Science Revision & Exam Practice

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1 AS Level Biology Summer Work Separate Science Revision & Exam Practice The booklet needs to be completed and handed in as part of the enrolment process on Thursday 20 th August 2015 Please ensure your name is clearly visible on the work.

2 Section 1 Osmosis Using your knowledge from GCSE, the internet and any books available answer ALL of the following questions. 1. What is diffusion? 2. What is meant by partially permeable? 3. Does a dilute sugar solution have a high or low volume of water? 4. What is osmosis? 5. What is meant by a polar molecule?

3 Exam Q Some substances move through membranes. A student set up an investigation. The student: tied a thin membrane across the end of a funnel put concentrated sugar solution in the funnel put the funnel in a beaker of water measured the level of the solution in the funnel every 30 minutes. The diagram shows the apparatus. The graph shows the results. (a) After 3 hours, the level of the solution in the funnel is different from the level at the start. Explain why, as fully as you can.

4 (b) The student repeated the investigation using dilute sugar solution instead of concentrated sugar solution. In what way would you expect the results using dilute sugar solution to be different from the results using concentrated sugar solution? Give the reason for your answer. (3)

5 Section 1.2 Active Transport 1. How does active transport differ from diffusion and osmosis? 2. Where does the energy for active transport come from? 3. Give an example of how active transport is used in animals?. 4. Give an example of how active transport is used in plants?

6 Exam Q The table shows the concentrations of three mineral ions in the roots of a plant and in the water in the surrounding soil. Mineral Ion Concentration in milimoles per kilogram Plant Root Soil Calcium Magnesium Potassium (a) (i) The plant roots could not have absorbed these mineral ions by diffusion. Explain why. (ii) Name the process by which the plant roots absorb mineral ions. (b) How do the following features of plant roots help the plant to absorb mineral ions from the soil? (i) A plant root has thousands of root hairs. (1) (ii) A root hair cell contains many mitochondria. (1) (iii) Many of the cells in the root store starch. (1) (Total 7 marks)

7 Section 1.3 The Lungs 1. List three adaptations of an exchange surface that makes gas exchange in humans an efficient process in many organisms 2. What are alveoli? 3. How are alveoli adapted for gas exchange? 4. Hoe does ventilation aid gas exchange? 5. Name four components of the respiratory system

8 6. Describe the changes in the thorax during inhalation. (remember to talk about the diaphragm, intercostal muscle, volume and pressure) 7. Describe the changes in the thorax during exhalation. Exam Q The human lung has about 80 million alveoli. (a) Give three features of the alveoli that allow large amounts of oxygen to enter the blood (b) (i) Name the process by which oxygen passes from the air into the blood.... (1) (ii) Breathing allows large amounts of oxygen to enter the blood. Explain how breathing does this. (3) (Total 6 marks)

9 Section 1.4 Exchange in the Gut 1. Why must the products of digestion get into the blood stream? 2. What is a villus 3. Why is it so important that the villi have a rich blood supply? 4. Describe the role of active transport in the small intestine..

10 Exam Q Read the following information about how the small intestine absorbs sugars. The blood absorbs glucose and some other sugars, like xylose, from the small intestine. Glucose molecules are the same size as xylose molecules, but glucose is absorbed more quickly than xylose. Experiments with pieces of intestine show that the uptake of oxygen by the intestine is 50 % higher in the presence of glucose than in the absence of glucose. Xylose does not have this effect on the uptake of oxygen. The cells lining the small intestine have many mitochondria. Explain how this information provides evidence that glucose is absorbed by the small intestine using active transport. (4) (Total 4 marks)

11 Section 1.5 Water loss in plants 1. What do we call the process by which water is lost from the leaves of a plant? How is this achieved? 2. What environmental conditions will increase the rate of transpiration? 3. What adaptations do leaves have that help to reduce water loss?

12 Exam Q Transpiration occurs mainly in the leaves of a plant. (a) (i) What is transpiration? (ii) Through which part of a leaf does most transpiration occur? (1) Some students set up the following apparatus. Cotton wool Water Balance A B The balances show the same mass at the start of the investigation. After 24 hours the mass of flask B was the same but the mass of flask A had changed. (i) Describe and explain the change to the mass of flask A. (3) (ii) Why did the students need to set up flask B? (1) (Total 7 marks)

13 Part 2 Transporting Materials Section 2.1 The Heart 1. Why is the human circulatory system known as a double circulatory system? 2. Name three structures present in the heart and describe their function 3. Why is the muscular wall around the left ventricle thicker than the right? 4. What do you call the artery that carries deoxygenated blood away from the heart? 5. What do you call the artery that carries oxygenated blood away from the heart?

14 (a) Exam style Question The table shows the effect of exercise on the action of one person s heart. At rest During exercise Heart rate in beats per minute Volume of blood leaving the heart in each beat in cm 3 Heart output in cm 3 per minute 5400 (i) Calculate the heart output for this person during exercise. Show clearly how you work out your answer. Answer =... cm 3 per minute (ii) During exercise, more oxygen is carried to the working muscles. Explain why this is helpful during exercise. (b) Give two other changes in the body that help to increase the amount of oxygen delivered to the working muscles during exercise (Total 6 marks)

15 2.1 Transport of Substances in Plants 1. Name the structure in plants that transports food Name the structure in plants that transports water Describe the structure and function of the phloem Describe the structure and function of the xylem

AQA B3.1 Movement of molecules in and out of cells LEVEL 3

AQA B3.1 Movement of molecules in and out of cells LEVEL 3 128 minutes 128 marks Page 1 of 29 Q1. Plants need chemical energy for respiration and for active transport. (i) Write a balanced chemical equation