Sug Ans Rp01e

Certificate Biology - New Mastering Basic Concepts

Suggested answers Revision paper 1

Suggested answers The University of Cambridge Local Examinations Syndicate/Midland Examining Group bears no responsibility for the example answers to questions taken from its past question papers which are contained in the textbooks.

Revision paper 1 Multiple-choice questions (p.72) 1

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Structured questions (p.72) 1

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A — cell membrane B — cytoplasm C — nucleus D — chloroplast E — vacuole Cell wall supports and gives the shape to the plant cell/protects the cell (any 1) Title Magnification The original magnification is 10 x 4 = 40 The new magnification is 5 x 10 = 50 The cell will appear larger under a higher magnification power.

1m x 5 1m 1m 0.5m 0.5m 1m 1m

Remove small bits from the organism and observe under the microscope. 1m Observe whether the cells had cell walls or not. It was a plant if the cells had cell walls. 1m i Remove small bits from different parts of the organism and observe under the microscope. 1m See whether the cells are different in size and shapes, and group together. 1m ii Organ level of organization — different tissues group together to form an organ to carry out specialized functions. 1m System level of organization — several organs and tissues work together to form a system that carries out a particular set of functions in a coordinated way. 1m A membrane with spaces that only allow small molecules to pass through. 1m For the egg in distilled water, there was a net movement of water molecules from the outside into the egg 1m

 Oxford University Press 2003

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Certificate Biology - New Mastering Basic Concepts

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Suggested answers Revision paper 1

as the water potential was lower inside the egg. 1m Thus the volume of the egg increased. 1m For the egg in concentrated salt solution, there was a net movement of water molecules from the egg to the salt solution 1m as the water potential was higher inside the egg. 1m The volume of the egg thus decreased. 1m The degree of difference in water potential across the differentially permeable membrane. 1m The temperature of the environment. 1m Gases 1m When the concentration of catalase in the tissue was high, the reaction rate was high and the rate of oxygen formation was fast. 1m Since the amount of hydrogen peroxide was the same in all test tubes, the shorter the time for bubbles to appear means the faster rate of reaction. 1m Thus the order of increasing catalase concentration was apple, potato tuber, mushroom, pork and pig's liver. 1m Step (1): Use equal weights of tissues. 1m Step (2): Ground each tissue with a fixed volume of distilled water with a mortar and pestle. 1m Step (3): Filter the tissue mixture and use the filtrate for step (2) in the experiment. 1m Catabolic reaction. 1m Both types of reactions. 1m Animals usually have a higher metabolic rate. 1m Most animals have movement and thus need more energy. 1m A — nucleus B — cell membrane C — cytoplasm cell membrane • cytoplasm • nucleus •

1m x 3 • is the place where chemical reactions take place • controls the cell • controls which substances pass into and out of the cell 2m 1m

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organs/systems

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i Substrate 1m ii Products of enzyme hydrolysis 1m The substrate attaches to an enzyme molecule at the active site. The substrate fits into an enzyme molecule like a key fits a lock; substrate is the lock and the enzyme is a key. 1m The enzyme speeds up the rate of reaction without itself being changed at the end of the reaction. 1m An aqueous medium with an appropriate pH is required. 1m The rate of enzyme activity can be controlled by adjustment of the temperature and pH. 1m It may be a slower reaction compared to the bursting of a balloon. 1m

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 Oxford University Press 2003

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