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Q1. Cells Scientists use a microscope to study how cells work. (a) The diagram shows a light microscope. Complete the sentence by putting a cross ( ) in the box next to your answer. To make the image of the cell appear larger you would (1) A turn the focusing wheel B change the objective lens C clean the stage D move the mirror (b) (i) Draw one straight line from each cell to the group of organisms to which it belongs. (2) (ii) Put a cross ( ) in the box next to your answer. Which plant cell structures use sunlight for photosynthesis? (1) A chloroplasts B cytoplasm C mitochondria D vacuoles (iii) The function of the cell membrane is to allow certain substances into and out of the cell. Describe how molecules like water can pass through a cell membrane but molecules like starch cannot. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. (c) A scientist looks at a cell with a microscope that has a magnification of times 40. The cell is 0.1 mm long. Calculate the size of the magnified image. (2) answer .................................................................................. Q2. Cells (a) The diagrams show a bacterial cell, a plant cell and an animal cell. Structure X is found in all three cells. (i) Complete the sentence by putting a cross ( ) in the box next to your answer. Structure X is the (1) A cell membrane B cell wall C cytoplasm D nucleus (ii) Many bacteria have one or more flagella whereas most animal cells have no flagella. State one other difference between a bacterial cell and an animal cell. (1) .............................................................................................................................................. (b) Scientists use microscopes to magnify cells. (i) Use words from the box to complete the sentences. (2) The magnification of a light microscope can be varied by changing the............................................................................ The electron microscope can magnify images...........................................................................than the light microscope. (ii) The diagram shows a sperm cell that has been magnified 100 000 times. Calculate the actual length of the sperm cell. (2) length of sperm cell = .................................................................... mm (iii) Explain why a human sperm cell contains more mitochondria than most other types of cell in the human body. (2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q3. Question number (a) Answer Mark B Question number (b)(i) (1) Answer Mark 1 mark for each correct line (2) Question number (b)(ii) A Question number (b)(iii) Question number (c) Answer Mark (1) Answer Acceptable answers a description including the following: cell membranes have small gaps/holes in them (1) water is small enough to fit through them/starch is too big to fit through them (1) (2) Answer 4 (1) mm (1) Mark Mark (2) Q4. Question Number (a)(i) Question Number (a)(ii) Question Number (b)(i) Question Number (b)(ii) Question Number (b)(iii) Answer A Answer Acceptable answers Acceptable answers bacterial cells have plasmids Any one of the following points • bacterial cells have a cell wall (animal cells do not) (1) • bacterial cells do not have a nucleus (animal cells do) (1) • bacterial cells have circular DNA / chromosomal DNA (animal cells do not) (1) Answer Acceptable answers • objective lens (1) • more (1) Answer Acceptable answers calculation (1) correct answer (1) = 0.00130 / 1.3 × 10-3 Answer An explanation including two of the following points • mitochondria are sites of respiration for energy (1) • sperm requires a lot of energy (1) • for movement / swimming / to move the flagellum (1) Acceptable answers Mark (1) Mark (1) Mark (2) Mark (2) Mark (2)