Biology - Year 9 Summer Exam with Complete detailed Answers Verified for Current Edition

What is respiration? The release of energy from glucose What are eukaryotes? Eukaryotes are organisms that have a membrane-bound nucleus and organelles inside their cells. They can be unicellular (only one cell) or multicellular (more than one cell). Practical: Investigating the effect of exercise on breathing (7) -Exercise increases the frequency and depth of breathing -This can be investigated by counting the breaths taken during one minute at rest and measuring average chest expansion over 5 breaths using a tape measure held around the chest -Exercise for a set time (at least 3 minutes). Immediately after exercising, count the breaths taken in one minute and measure the average chest expansion over 5 breaths -Following exercise, the number of breaths per minute will have increased and the chest expansion will also have increased -This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand. -If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid -This can be tested by seeing how long it takes after exercise for the breathing rate and depth to return to normal – the longer it takes, the more lactic acid is being produced. Describe the common features shown by animals (5) -Eg: humans (mammals), butterflies (insects) -They are multicellular -Cells contain a nucleus but no cell walls or chloroplasts -Feed on organic substances made by other living things -Store carbohydrates as glycogen Describe the common features shown by plants (6) -Eg: herbaceous legumes (peas), cereals (wheat) -They are multicellular -Cells contain a nucleus, chloroplasts and cellulose cell walls -They all feed by photosynthesis -They store carbohydrates as starch or sucrose -Contain a large, central cell vacuole Describe the common features shown by fungi (5) -E.g. moulds, mushrooms, yeast -Most are multicellular with a mycelium of thread-like structures called hyphae which have many nuclei but some are single-celled (eg yeast is single celled) -Cells have nuclei and cell walls made from chitin -Feed by saprotrophic (on dead or decaying material) or parasitic (on live material) nutrition by secreting extracellular enzymes onto the food -May store carbohydrates as glycogen Describe the common features shown by protoctists (3) -E.g. Amoeba (like an animal), Chlorella (like a plant) -Most are unicellular -E.g. Amoeba (like an animal), Chlorella (like a plant) Most are unicellular All have a nucleus; some may have cell walls and chloroplasts, meaning some may have cell walls and chloroplasts, meaning some protoctists photosynthesize like plants and some feed on organic substances made by other living things like animals practical: investigate diffusion using living system (6) During inhalation, oxygen-rich air enters alveoli There is a higher concentration of oxygen in the alveoli than in the flood running past the alveoli Oxygen will diffuse out of alveoli down the concentration gradient into the blood At the same time, there is a higher concentration of carbon dioxide in the blood (from respiration) than in the alveoli Carbon dioxide will diffuse out of blood down the concentration gradient into the alveoli This is how gas exchange takes place in mammals Describe the common features shown by Prokaryotic organisms such as bacteria (5) -Prokaryotes do not have a membrane-bound nucleus or membrane-bound organelles inside their cells. -E.g. bacteria (Lactobacillus d. bulgaricus (rod-shap