1 PAKISTAN SCHOOL MUSCAT FIRST TERM - ACADEMIC SESSION (2023-24) Subject: Class: Section: Topic: Photosynthesis and carbon cycle. (Questions-answers) Worksheet # Name: Questions and Answers:- Date: Q1: How plants make food? Ans: - Plants make food by photosynthesis. Photo means ‘light’, synthesis means ‘making’. So photosynthesis means ‘making with light’. Q2: a) What are the reactants in photosynthesis? Ans: - Water, Carbon dioxide, Energy from sunlight. b) Write the products in photosynthesis? Ans: - Glucose and carbon dioxide. Q3: Write the word equation for photosynthesis. Ans: - water + carbon dioxide glucose + oxygen Q4: Why is photosynthesis important? Ans: - Because it provides nutrients in the form of glucose to other living organisms. And because it provides oxygen for living organisms. Q5: What are the similarities and differences between photosynthesis and respiration? Ans: - Similarities: They are both chemical reactions. They both happen inside cells. They both involve energy changes (energy transfer). They both involve glucose, oxygen, carbon dioxide and water. Differences: Respiration happens in all living cells, but photosynthesis only happens in some plant cells. Respiration happens in cytoplasm and mitochondria, but photosynthesis happens in chloroplasts. Photosynthesis needs light, but respiration does not. 2 The reactants in respiration are the products in photosynthesis, and vice versa. In photosynthesis, energy from sunlight is transferred to chemical energy in glucose. In respiration, energy in glucose is released for the cell to use. Q6. How light intensity affect photosynthesis?(page 11,12) Answer. As light intensity increases, the rate of photosynthesis will increase. Q7. Test a leaf for starch.(page 17.18) Place the leaf in a Petri dish and pour iodine solution over it. The appearance of a blue-black colour on the leaf indicates the presence of starch. The absence of starch is indicated by brown colouration. Q8. Which surface of leaf has stomata?(19 page) All the surfaces of the leaf have some amount of stomata. Stomata are tiny pores present on the epidermis of a leaf that help in the exchange of gases and transpiration. Generally lower surface of the leaf has more number of stomata, Q9. Write the importance of magnesium and nitrate minerals. (One for magnesium and two uses for nitrate) (Page 21) Answer. Magnesium. It makes chlorophyll in the plant. Nitrate.1. It helps the plant in making protein from carbohydrates. 2.it also makes chlorophyll. Q10.What is the effect of fertilisers on plant growth? (page 22) Fertilizers provide crops with nutrients like potassium, magnesium, and nitrogen, which allow crops to grow bigger, faster, and to produce more food. Q11.Define carbon cycle. The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth into organisms and then back into the atmosphere. The carbon cycle is nature's way of reusing carbon atoms, over and over again. Q12.Define combustion. (Page 31) The process where a substance burns in the presence of Oxygen, giving off heat and light in the process. 3 Q13.Describe the formation of coal.(page 31) Q14.Describe the formation of oil and natural gas.(page 30) Q15.Explain why fossil fuels are non-renewable resources? Fossil fuels like coal and petroleum are formed from the decayed plants and animals buried under the Earth. It takes millions of years for them to decay and convert into fossil fuels. So, fossil fuels like coal, petroleum, etc cannot be replenished easily and hence, it is considered as a non-renewable source of energy. Topic 1.4 Climate change. Q1. Describe what an asteroid is, and where asteroids are found. ANSWER. Asteroids are small, rocky objects that orbit the Sun.. Asteroids, sometimes called minor planets. They can be found orbiting our Sun between Mars and Jupiter within the main asteroid belt. Q2. Outline three different ways in which 67 million years ago would have made it difficult for plants and animals to survive.(PAGE 36) 1.Animals and plants died where the asteroids fell. They cause shock waves and high temperatures and killed animals and plants. 2.Asteroids threw huge quantities of dust and rocks in the atmosphere and caused destruction. 3.They created massive tsunami and causes destruction. Q3. What are the impacts of climate change? 1.More extreme weather events. 2.less predictable rainfall. 3.rising sea level.
