Page 1 What is the role of the nucleus? What is the role of the cytoplasm? What is the role of the cell membrane? What is the role of the mitochondria? What is the role of ribosomes? What is the role of the cell wall found in plant cells and algal cells? What is the role of chloroplasts, found in plant cells? What is the role of the permanent vacuole found in plant cells. What are the main parts of a bacterial cell? What are the main parts of a yeast cell? How do dissolved substances move in and out of cells? What is the definition of diffusion?
Page 2 The cytoplasm is where most of the chemical reactions of the cell take place. The nucleus controls the activities of the cell. The mitochondria are where most energy is released in respiration. The cell membrane controls the passage of substances into and out of the cell. The cell wall of plant cells and algal cells strengthens the cell. The ribosomes are where protein synthesis takes place. The permanent vacuole, found in plant cells, contains cell sap. Chloroplasts, found in plant cells, absorb light energy to make glucose in photosynthesis. Yeast are single-celled. They have a nucleus, cytoplasm and a membrane surrounded by a cell wall. Bacterial cells have a cytoplasm, a cell membrane and a cell wall. They do not have a nucleus. Diffusion is the spreading of particles from a region where they are in a higher concentration to a region where they are in a lower concentration. Dissolved substances move in and out of cells by diffusion.
Page 3 How does the concentration of a substance affect the rate of diffusion? How does oxygen, needed for respiration, pass through cell membranes? What is the definition of a tissue? What is the role of muscular tissue. What is the role of glandular tissue? What is the role of epithelial tissue? What is the definition of an organ? What are the tissues found in the stomach and what are their functions? What is meant by an organ system and give an example. What are the glands in the digestive system and what do they produce? Where does digestion take place in the digestive system? What is the role of the liver in the digestive system?
Page 4 Oxygen, needed for respiration, passes through cell membranes by diffusion. The greater the difference in concentration, the faster the rate of diffusion. Muscular tissue brings about movement. A tissue is a group of cells with a similar structure and function. Epithelial tissue covers some parts of the body. Glandular tissue produces substances such as enzymes and hormones. The stomach has: muscle tissue to churn the contents glandular tissue to produce digestive enzymes epithelial tissue to cover the inside and outside of the stomach An organ contains different tissues working together to carry out a function e.g. the stomach. The glands in the digestive system are the pancreas and salivary glands. They produce digestive enzymes. Organ systems are groups of organs working together to carry out a function. An example is the digestive system. In the digestive system, the liver produces bile. Digestion takes place in the stomach and small intestine.
Page 5 In the digestive system, where does the absorption of soluble food molecules take place? In the digestive system, where is water absorbed from undigested food, producing faeces? In the leaf, what is the function of the epidermal tissues? In the leaf, what is the function of the mesophyll? In the plant, what is the function of the phloem? In the plant, what is the function of the xylem? State the word equation for photosynthesis. During photosynthesis, which molecule absorbs light energy? Where is the plant cell do we find chlorophyll, which absorbs light energy? Where does the carbon dioxide used in photosynthesis come from? Where does the water used in photosynthesis come from? State three factors that can limit the rate of photosynthesis.
Page 6 In the digestive system, water is absorbed from undigested food in the large intestine, which produces faeces. In the digestive system, the absorption of soluble food molecules takes place in the small intestine. In the leaf, the mesophyll carries out photosynthesis. In the leaf, the function of the epidermal tissue is to cover the plant. In the plant, the function of the xylem is to transport water and minerals from the roots to the leaves. In the plant, the function of the phloem is to transport dissolved sugars from the leaves to other parts e.g. roots. During photosynthesis, light energy is absorbed by chlorophyll. The word equation for photosynthesis is: carbon dioxide + water glucose + oxygen The carbon dioxide used in photosynthesis comes from the air. In the plant cell, we find chlorophyll in the chloroplasts. The rate of photosynthesis can be limited by shortage of light low temperature shortage of carbon dioxide The water used in photosynthesis comes from the soil.
Page 7 State why oil burners and artificial lights are often used in greenhouses. During photosynthesis, the sugar glucose is produced. How is this glucose stored? How do plant cells use the glucose produced in photosynthesis to release energy? State three molecules made using the glucose produced in photosynthesis. Which ion absorbed from the soil, is needed by plants to make proteins? State four factors that affect the number of animals in a habitat. State four factors that affect the number of plants in a habitat. Describe how the distribution of organisms can be determined using random sampling with quadrats. Describe how the distribution of organisms can be determined using sampling along a transect. Proteins are long chains of which molecule? After a protein is formed, what must happen before it can carry out its function? State four functions of proteins.
Page 8 The glucose produced in photosynthesis is stored as the molecule starch. The rate of photosynthesis is limited by light (which is provided by artificial lights) and carbon dioxide and low temperature. Oil burners release carbon dioxide and heat. The glucose produced in photosynthesis is used to make: fat/oil for storage cellulose to strengthen the cell wall proteins Plant cells use the glucose produced in photosynthesis to release energy in respiration. The number of animals in a habitat are affected by: temperature availability of nutrients availability of water availability of oxygen Plants need the nitrate ion, which is absorbed from the soil in order to make proteins. Randomly throw quadrat. Count the number of organisms in quadrat. Repeat in new location. The number of plants in a habitat are affected by: temperature availability of water availability of light availability of carbon dioxide Proteins are long chains of amino acids. Use a tape measure to make a transect. Place quadrat at first point and count number of organisms in quadrat. Now move quadrat to next point on transect and repeat. Proteins can be: structural eg muscles hormones antibodies enzymes Proteins must fold into a specific shape before they can function.
Page 9 Why do enzymes not work at high temperatures? How does ph affect enzymes? State three places where the enzyme amylase is produced. What is the function of the enzyme amylase? State three places where the enzyme protease is produced. What is the function of the enzyme protease? State two places where the enzyme lipase is produced. What is the function of the enzyme lipase? Which acid is produced in the stomach? Where is bile produced? What is the function of bile? Describe why enzymes are used in biological detergents (eg washing powders).
Page 10 Different enzymes work better at different phs. For example protease in the stomach works best in acidic conditions. High temperatures change the shape of enzymes (they are denatured). If the shape is incorrect, enzymes cannot function. The enzyme amylase breaks down starch into sugars. The enzyme amylase is produced in the salivary glands, the pancreas and the small intestine. The enzyme protease breaks down proteins into amino acids. The enzyme protease is produced by the stomach, the pancreas and the small intestine. Lipase breaks down lipids (fats and oils) into fatty acids and glycerol. The enzyme lipase is produced by the pancreas and small intestine. Bile is produced by the liver. The stomach produces hydrochloric acid. Biological detergents contain protease and lipase. These are more effective at removing stains at low temperatures than other detergents. In the small intestine, bile neutralises the acid from the stomach contents. This is because enzymes in the small intestine work best in alkaline conditions.
Page 11 Describe three uses of enzymes in industry. Why are enzymes used in industry? What is meant by aerobic respiration and where in the cell does this take place? State the equation for aerobic respiration. State four uses of the energy released during respiration. State two changes that take place during exercise and explain their functions. What is the role of glycogen in muscles? What is meant by anaerobic respiration? State the equation for anaerobic respiration. What is meant by the oxygen debt? (HIGHER TIER). Vigorous exercise can result in fatique. What causes this? How many chromosomes are found in a normal human cell?
Page 12 Enzymes allow reactions to take place at lower temperatures, saving money. However, enzymes are expensive and are denatured by high temperature. Examples of enzymes in industry are: Protease used to pre-digest the protein in baby foods Carbohydrase (eg amylase) used to convert starch into sugar syrup Isomerase converts glucose syrup to fructose syrup. Fructose is very sweet and is used in small quantities in slimming food. The equation for aerobic respiration is: glucose + oxygen carbon + water + energy dioxide Aerobic respiration requires oxygen and takes place mainly in mitochondria. During exercise, the heart rate increases and the rate and depth of breathing also increases. This increases the flow of blood contain oxygen and glucose to the muscles and removes carbon dioxide. Four uses for the energy released during respiration are: to build larger molecules from smaller ones e.g. proteins from amino acids. Muscle contraction in animals Keeping a constant body temperature in mammals and birds In plants, to build up sugars and nitrates into amino acids. Anaerobic respiration is the release of energy without the need for oxygen. In muscles, glycogen is a store of glucose. Glycogen can be converted back to glucose during exercise. Anaerobic respiration releases much less energy than aerobic respiration as the remaining lactic acid contains a lot of energy. After exercise stops, the lactic acid is oxidised to carbon dioxide and water. This requires oxygen, which is the oxygen debt. The equation for anaerobic respiration is: glucose lactic acid + energy In a normal human cell, there are 23 pairs of chromosomes. Lactic acid builds up during vigorous exercise and this causes fatigue in the muscles. The lactic acid is removed by the blood.
Page 13 What name is given to the cell division that produces normal human cells in growth and repair of damaged tissue. What are the two stages in mitosis? How many chromosomes are found in human gametes? Which cells divide to form gametes in humans. What type of cell division produces gametes? Describe the stages of meiosis (HIGHER TIER). What do we call the process when gametes join together? What do we call the process where cells change and specialise to their roles? What do we call cells that can differentiate into any other kinds of cells? State two places we can find these cells. How could stem cells be useful in medicine? What is meant by asexual reproduction? Why does sexual reproduction lead to variation?
Page 14 In mitosis, first all of the chromosomes are copied. Then the cell divides once to produce two genetically identical body cells. Mitosis produces normal human cells in growth and to repair damaged tissue. In humans, sperm are produced in the testes. Eggs are produced in the ovaries. Gametes (sperm and egg) contain only one set of chromosomes (ie not in pairs). Human gametes have 23 single chromosomes. In meiosis, first the chromosomes are copied. The cell then divides twice, producing four gametes. Each gamete has a single cell of chromosomes. Gametes are produced by meiosis. When cells change and specialise, this is called differentiation. Gametes joining together is called fertilisation. Stem cells could be used in medicine for example to treat conditions such as paralysis. Stem cells can differentiate into any other kinds of cells. We find these in human embryos and in adult bone marrow. In sexual reproduction, when gametes fuse, the offspring has alleles from both parents. Asexual reproduction does not involve gametes. It takes place by mitosis. The offspring are clones of the parent.
Page 15 What are the sex chromosomes for a: female male What is meant by an allele? What is meant by a dominant allele? What is meant by a recessive allele? What molecule is found in chromosomes and what is the structure of this molecule? What is a gene? How do genes function? (HIGHER TIER) How does DNA fingerprinting work? What is polydactyly and how is it inherited? What is cystic fibrosis and how is it inherited? What do we call the process where an embryo is checked for a defective allele? What is the main evidence that living organisms evolved from simpler life forms?
Page 16 An allele is a form of a gene. The sex chromosomes are: female = XX male = XY A recessive allele can only control a characteristic when there are two copies of that allele. A dominant allele will control a characteristic even when there is only one copy of that allele. A gene is a small section of DNA which controls a characteristic. Chromosomes are made of the molecule DNA. DNA has a double helix structure. Each person (apart from identical twins) has unique DNA. This means that they can be identified using DNA fingerprinting Each genes codes for a particular combination of amino acids which make a specific protein Cystic fibrosis is a disorder of cell membranes. It is a recessive allele. This means that you can carry the allele without having the actual disorder. In order to have the disorder, you must inherit two copies of the allele, one from each parent. Polydactyly (extra fingers or toes) is a dominant allele. It can be inherited from only one parent. The main evidence that living organisms evolved from simpler life forms is fossils. Checking an embryo for a defective allele is called embryo screening.
Page 17 What are fossils? State four ways that fossils can be formed. State two reasons why fossil remains are incomplete. How can extinction be caused? What is required for a new species to form? Describe the stages of speciation (HIGHER TIER).
Page 18 Fossils can be formed as follows: from the hard parts of animals that do not decay from other parts of organisms which have not decayed due to conditions e.g. low temperature parts of an organism are replaced with other materials as they decay preserved traces of organisms e.g. footprints Fossils are the remains of organisms from many years ago, found in rocks. Extinction can be caused by: New predators Diseases Competitors Catastrophes eg volcanos Gradual environmental change Fossil remains can be incomplete because: many early forms of life were softbodied, which leave few fossils. fossils can be destroyed e.g. by earth movements Four stages of speciation: 1. Isolation 2. Each population has a wide range of alleles. 3. In each population, advantageous alleles allow organisms to survive and reproduce (natural selection) 4. After time, the populations are so different that they can no longer interbreed (speciation). New species can form when a population is split into two separate populations e.g. by a river. Scientists call this isolation.
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