Worksheet Answer Key - Cells & Biology - PDF

ANSWER KEY CHAPTER-2 2.2: CELLS Question Answer ---------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------...

ANSWER KEY CHAPTER-2 2.2: CELLS Question Answer ---------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1 Chloroplasts contain [chlorophyll], a pigment that absorbs light energy. Mitochondria are the site of aerobic [respiration], a process that produces [ATP] that provides cells with [energy]. This theory suggests that the larger cell may have provided the smaller cell with [protection], in exchange for [glucose (and energy)]. 2 a i Ribosomes are the site of protein synthesis. Viruses consist of nucleic acid surrounded by a protein coat, which is therefore produced by the host cell ribosomes. 2 a ii To reproduce, viruses require energy, derived from ATP. This ATP is produced by the mitochondria in the host cell. 2 b Bacterial cells have another layer surrounding the cell wall called the capsule. +-----------------------------------+-----------------------------------+ | Question | Answer | +===================================+===================================+ | **2** | cell membrane -- A very thin | | | layer surrounding the cytoplasm | | | of every cell; it controls what | | | enters and leaves the cell. | | | | | | ribosomes -- Tiny structures | | | found in animal cells and plant | | | cells. They are so small that we | | | can only see them with an | | | electron microscope. | | | | | | cell wall -- A tough layer | | | outside the cell membrane; found | | | in the cells of plants, fungi\ | | | and bacteria. | | | | | | mitochondria -- Small structures | | | in a cell, where aerobic | | | respiration releases energy\ | | | from glucose. | | | | | | nucleus -- A structure containing | | | DNA in the form of chromosomes. | | | | | | vacuole -- A fluid-filled space | | | inside a cell, separated from the | | | cytoplasm by a membrane. | | | | | | cytoplasm -- The jelly-like | | | substance that forms the | | | \'background material\' of all | | | cells. | +-----------------------------------+-----------------------------------+ CHAPTER-3 +-----------------------+-----------------------+-----------------------+ | Question | Answer | | +=======================+=======================+=======================+ | 4 a | Mango slices swell up | | | | when placed into | | | | water because the | | | | water has a | | | | [higher] | | | | water potential than | | | | the mango tissue. | | | | Therefore, water | | | | moves | | | | [into] | | | | the mango in the | | | | process of | | | | [osmosis] | | | |. | | +-----------------------+-----------------------+-----------------------+ | 4 b | Mango slices swell up | | | | faster when placed | | | | into warm water | | | | because at higher | | | | temperature, water | | | | molecules have more | | | | [kinetic] | | | | energy. Therefore, | | | | water moves more | | | | [quickly] | | | | into the mango in the | | | | process of | | | | [osmosis] | | | |. | | +-----------------------+-----------------------+-----------------------+ | Question | Answer | Marks | +-----------------------+-----------------------+-----------------------+ | 1 | The completed table | 3 | | | will look like this: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Diffusion | | | | | | | | Osmosis | | | | Active tr | | | | ansport | | | | | | | | | | | | | | | | | | | | Does it involv | | | | e random movements? | | | | of particles?< | | | | /td> | | | | | | | | | | | | | | | | | | | | | | | | Does a partially | | | | permeable membrane ha | | | | ve to be present? | | | | | | | | | | | | | | | | | | | | | | | | Does it involve p | | | | articles moving down | | | | their concentration g | | | | radient? | | | | | | | | | | | | | | | | | | | | | | | | Does it involve p | | | | articles moving up th | | | | eir concentration gra | | | | dient? | | | | | | | | | | | | | | | | | | | | | | | | Does the cell | | | | use energy to make? | | | | it happens? | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | **\[1 mark for each | | | | correct column\]** | | +-----------------------+-----------------------+-----------------------+ **CHAPTER-4** +-----------------------+-----------------------+-----------------------+ | Question | Answer | | +=======================+=======================+=======================+ | **1** | A | | +-----------------------+-----------------------+-----------------------+ | **2 a** | The completed diagram | | | | is as follows. | | | | | | | | A picture containing | | | | shape Description | | | | automatically | | | | generated | | +-----------------------+-----------------------+-----------------------+ | **2 b** | **i** Starch is an | | | | energy storage | | | | molecule in plants. | | | | | | | | **ii** Glucose is | | | | used in respiration | | | | in plants and | | | | animals. | | +-----------------------+-----------------------+-----------------------+ | **3** | The suggested labels | | | | on the diagram should | | | | be positioned as | | | | follows. | | +-----------------------+-----------------------+-----------------------+ | Question | Answer | Marks | +-----------------------+-----------------------+-----------------------+ | 1 | The completed table | 5 | | | is as follows. | | | | | | | | | | | | **C** **H** **O** | | | | **N** **S** ** | | | | P** | | | | ------------------ | | | | ------- ------- ----- | | | | -- ------- ------- -- | | | | ----- | | | | **Carbohydrate** | | | | | | | | | | | | **Protein** | | | | | | | | | | | | **Lipid** | | | | | | | | | | | | **DNA** | | | | | | | | | | | | | | | | **\[1\]** is awarded | | | | for each correct | | | | column (C is | | | | provided) | | +-----------------------+-----------------------+-----------------------+ | 2 | First, a small volume | 3 | | | of blue Benedict's | | | | solution is added to | | | | the piece of carrot. | | | | **\[1\]** Next, the | | | | mixture is heated to | | | | at least 80 °C. | | | | **\[1\]** It is | | | | important during this | | | | procedure to avoid | | | | direct heating (e.g. | | | | with a Bunsen burner) | | | | -- a water-bath | | | | should be used. | | | | Safety goggles or | | | | glasses are also | | | | necessary. **\[1\]** | | +-----------------------+-----------------------+-----------------------+ +-----------------------+-----------------------+-----------------------+ | Question | Answer | Marks | +=======================+=======================+=======================+ | 6 | C **\[1\]** | 1 | +-----------------------+-----------------------+-----------------------+ | 7 a | The lipase in | 3 | | | test-tube A digests | | | | the lipids in the | | | | milk, **\[1\]** into | | | | fatty acids (and | | | | glycerol). **\[1\]** | | | | The fatty acids | | | | reduce the pH of the | | | | solution, meaning | | | | that the indicator | | | | | | | | becomes yellow. | | | | **\[1\]** | | +-----------------------+-----------------------+-----------------------+ | 7 b | The presence of | 2 | | | boiled enzyme, which | | | | is denatured, means | | | | that lipids will not | | | | be digested, and so | | | | the pH of the | | | | solution will not | | | | change. **\[1\]** | | | | This shows that the | | | | enzyme is responsible | | | | for lipid digestion. | | | | **\[1\]** | | +-----------------------+-----------------------+-----------------------+ | 7 c | The measurement of | 1 | | | colour change is | | | | subjective / open to | | | | interpretation. | | +-----------------------+-----------------------+-----------------------+ | 8 a | An increase in | 3 | | | temperature increases | | | | enzyme activity until | | | | this reaches a | | | | plateau at | | | | (approximately 50 | | | | degrees Celsius). | | | | **\[1\]** This is | | | | because the kinetic | | | | energy of enzyme and | | | | substrate molecules | | | | increases, which | | | | collide more | | | | frequently, and form | | | | a greater number of | | | | enzymes--substrate | | | | complexes per unit | | | | time. **\[1\]** The | | | | steepest increase in | | | | enzyme activity is | | | | between 30 and 40 | | | | degrees Celsius. | | | | **\[1\]** | | +-----------------------+-----------------------+-----------------------+ | 8 b | At temperatures above | 3 | | | 50 degrees Celsius, | | | | the kinetic energy of | | | | the enzyme increases | | | | so much that it | | | | denatures. **\[1\]** | | | | This causes the | | | | active site to change | | | | shape. **\[1\]** This | | | | means that fewer | | | | enzyme--substrate | | | | complexes form per | | | | unit time, and the | | | | activity of the | | | | enzyme reduces. | | | | **\[1\]** | | +-----------------------+-----------------------+-----------------------+ 9\. G 10\. i. Reproduction ii\. Sensitivity iii\. Nutrition 11\. C 12\. Cytoplasm Cell membrane 13\. any relevant answer MULTIPLE CHOICE QUESTI0NS: +-----------------------------------+-----------------------------------+ | Question | Answer | +===================================+===================================+ | 14 | C | +-----------------------------------+-----------------------------------+ | 15 | Any three from: | | | | | | growth, sensitivity, respiration, | | | reproduction, excretion, | | | nutrition | +-----------------------------------+-----------------------------------+ | 16 | Any two from: | | | | | | nucleus, cell membrane, | | | cytoplasm, mitochondria | +-----------------------------------+-----------------------------------+ | 17 | Suggested answers: | | | | | | **a** Cell -- red blood cell; | | | **b** Tissue -- blood; **c** | | | Organ -- heart; **d** Organ | | | system -- circulatory | +-----------------------------------+-----------------------------------+ | 18 | **a** True; **b** True; **c** | | | False; **d** False; **e** True | +-----------------------------------+-----------------------------------+ | 19 |  | +-----------------------------------+-----------------------------------+