Biology GCSE (B2) Questions

Transcription

1 Biology GCSE (B2) Questions Question Answer 1 Describe the structure of DNA A double helix with the two strands linked by a series of paired bases; twisted ladder 2 How do the bases pair up? Adenine with Thymine, and Guanine with Cytosine 3 Genes contain the code for making Proteins what? 4 Name a useful protein that can be Insulin produced by transferring the relevant gene into bacteria. 5 What do we call it when humans Genetic modification transfer useful genes from one species to another? 6 What is fermentation? When microorganisms use an external food source to obtain energy, thereby changing some of the substances around them e.g. glucose ethanol 7 What is a fermenter? A vessel used to cultivate microorganisms 8 Name 6 conditions that have to be Aseptic conditions maintained in a fermenter to Supply of food/nutrients maximise growth of the Optimum temperature microorganisms Optimum ph Oxygen/air supply 9 What are the advantages of using microorganisms for food production? Agitation/stirring Rapid growth, easy to grow Production is independent of climate Waste products from industry can be used as a food source for the microbes 10 A protein is a long string of many Amino acids what? 11 Where does transcription take place? In the nucleus. What does the m stand for in Messenger. mrna? 12 Where does translation take place? In the cytoplasm. Ribosomes translate the Name the organelle that translates message, and they re found in the the mrna message into protein cytoplasm. 13 What is a triplet (or codon)? A series of three DNA bases that code for a particular amino acid. 14 Name the small RNA molecule that Transfer RNA (trna) the ribosome matches to the mrna triplets.

2 15 Give three differences between DNA and RNA 16 What is the difference between respiration and breathing? 17 Give the word equation for respiration 18 How are gases exchanged in the lungs? 19 How are gases exchanged in respiring tissues? 20 What happens to the rates of respiration and gas exchange during exercise? Why? 21 What happens inside our bodies during vigorous exercise? RNA has ribose instead of deoxyribose RNA is single stranded, DNA is double stranded RNA has Uracil instead of Thymine Respiration is a chemical reaction that happens in every cell. It releases energy from glucose. Breathing is ventilation, a mechanical process in which the lungs inflate and deflate. Glucose + oxygen carbon dioxide + water. Oxygen diffuses from the alveoli into the capillaries, and carbon dioxide diffuses from the capillaries into the alveoli Oxygen diffuses from the capillaries into the respiring cells, and carbon dioxide diffuses from the respiring cells into the capillaries They increase because more energy is required by the muscle cells Oxygen cannot be delivered at a high enough rate so the cells carry out anaerobic respiration to get enough energy Lactic acid. Cramp. 22 What is the product of anaerobic respiration? What can it cause? 23 What is mitosis? Cell division for growth and repair 24 What is meiosis? Cell division for making gametes (sex cells) 25 Explain the differences between mitosis and meiosis. Mitosis results in 2 daughter cells, meiosis in 4 Mitosis produces diploid daughters, meiosis haploid Mitosis gives daughter cells that are genetically identical to parent cells, meiosis gives genetically different daughter cells 26 What do haploid and diploid mean? Haploid: having half the normal number of chromosomes Diploid: having the full complement of chromosomes 27 How many chromosomes do humans have? 46 (23 pairs)

3 28 Give four ways we can measure the growth of an organism Size Length/height Wet mass Dry mass 29 What is cell elongation? When the length of a plant cell increases in response to a stimulus e.g. light causing the plant to grow towards or away from the stimulus 30 What is differentiation? When cells specialise; stem cells divide to give new cells with particular features that allow them to perform a particular function 31 Why are scientists interested in stem cells? 21 What is the name given to the maximum number of times a cell can divide? They can divide to give any type of cell. Therefore: They could be used to treat illnesses like Parkinson s and cancer They could be used to produce organs for transplant, or new limbs or tissues to repair skin, heart etc They can be used to study cell division and differentiation The Hayflick limit 33 Which cells have no Hayflick limit? Stem cells and cancer cells 34 Why is termination of pregnancy generally illegal after 24 weeks? 35 Name three factors that can influence height in humans 36 Name six factors that can affect the growth and distribution of plants Because after 24 weeks a significan proportion of foetuses are viable. Thjis means that their organs are developed enough for them to survive outside the womb. Genes, hormones and nutrition - nutrients - light - temperature - carbon dioxide - oxygen - plant hormones 37 How are seedless fruits produced? A plant hormone is sprayed onto the unpollinated flowers. This makes them develop into fruits even though fertilisation hasn t taken place. 38 What is regeneration? The process by which some animals can re-grow body parts (e.g. newts, spiders, worms, starfish) 39 What is selective breeding (artificial Where animals or plants with desirable selection)? characteristics are chosen to breed from 40 Why might we selectively breed - improve the quality of milk from cattle

4 some organisms? 41 What are the two main stages in cloning a mammal? 42 What are the similarities and differences between plant and animal cells? 43 Name the green pigment found in chloroplasts 44 What is the word equation for photosynthesis? 45 Name some ways that humans utilise plants. 46 Name the factors that can limit the rate of photosynthesis - increase the number of offspring in sheep - increase the yield from dwarf wheat and other cereal crops -the replacement of the nucleus in an egg cell with a diploid nucleus from a mature cell (nuclear transfer) - stimulation of the diploid nucleus to divide Similarities: both have nuclei, cytoplasm and membranes. Differences: only plants have vacuoles, cell walls and chloroplasts Chlorophyll Carbon dioxide + water glucose + oxygen Food Fuel Shelter Medicine Clothing Paper Aesthetics Availability of Water Availability of nutrients/minerals Availability of carbon dioxide Light intensity Temperature magnesium, nitrogen, phosphorus and potassium Active transport. This requires energy from respiration Carbon and Nitrogen 47 Name the 4 main mineral salts that are required for healthy plant growth 48 How do plants take up minerals from the soil? 49 Name two important elements that are continually recycled from one chemical compound to another by the activity of plants, animals and microbes. 50 What is a biosphere? A self-contained structure that holds all the plants and animals needed for a sustainable environment 51 What is the name of the process that occurs when sewage or fertilisers pollute waterways, resulting in the loss of oxygen from the water? 52 What is the largest single reason for the current observable massive environmental changes such as deforestation, climate change and pollution? Eutrophication Human populations are growing unsustainably 53 How can we maximise energy Optimum feeding/growing conditions.

5 transfer in food production? Disease and predator control 54 What is interdependence? The mutual dependence of organisms within an ecosystem 55 What is adaptation? Changing to suit environmental conditions 56 What do we call the battle between Competition different types of organism for a resource? 57 What do we call it when one animal Predation hunts, kills and eats another animal? 58 Name three greenhouse gases Carbon dioxide, methane, water vapour 59 Name three air pollutants not Sulphur dioxide, nitrogen oxides, CFCs mentioned in the previous question. 60 What is a living indicator? Give an Evidence of the effects of pollution example. shown on an organism e.g. growth of lichens (inhibited by acidic gases), rates of skin cancer (CFCs), populations of 61 What is a non-living indicator? Give an example. 62 Give three examples of extreme environments aquatic invertebrates (water pollution) Evidence of the effects of pollution shown on a non-living aspect of the environment e.g. average global temperature (greenhouse gases), ozone depletion (CFCs). Hydrothermal (deep sea) vents Antarctic High altitudes 63 Why is it good to recycle? It reduces the demand for resources, and reduces the problem of waste disposal. In some cases it can save energy. 64 Name three conservation management techniques. 65 Why does conservation lead to greater biodiversity? Reforestation, coppicing and replacement planting It maintains a variety of habitats, and reduces flooding and desertification. This leads to a greater number of species having a suitable habitat and a reduction in the rate of extinction.