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Description
Flashcards by Laila Charlton, updated more than 1 year ago
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Created by Laila Charlton
over 7 years ago
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| Question | Answer |
| Photosynthesis | Photosynthesis is an endothermic reaction in which light transfers energy from the environment to chloroplasts of cells. Plants and algal cells photosynthesise to make food. Photosynthesis happens in the chloroplasts of cells. It requires chlorophyll pigment and is controlled by enzymes. |
| Equation for photosynthesis | Light Carbon dioxide+water --> Glucose+ oxygen Chlorophyll |
| Factors affecting photosynthesis | Factors that affect photosynthesis are light intensity, carbon dioxide concentration, temperature and the amount of chlorophyll. If one of these factors is not in a sufficient amount it will become a limiting factor so that photosynthesis levels off at a constant rate |
| Light intensity | As light intensity increases the rate of photosynthesis increases until it levels off. This happens because light energy is needed for photosynthesis. It levels off because there is another limiting factor such as carbon dioxide or temperature |
| Temperature | As temperature increases the rate of photosynthesis increases because the particles have more kinetic energy to collide and react. The rate of photosynthesis decreases because the enzymes have denatured |
| Uses of Glucose | Glucose is converted into starch, starch is insoluble and compact therefore ideal for storage. It is used to produce cellulose which forms cell walls giving it additional strength. It is used in respiration to release energy. Glucose is used to produce fats or lipids for storage, and to produce amino acids for making proteins. Nitrate ions from the soil are also needed for making proteins. |
| Aerobic respiration | Aerobic respiration is an exothermic reaction which happens continuously in the mitochondria. It transfers/releases energy and requires oxygen. It is controlled by enzymes. Glucose + oxygen --> Carbon dioxide + water + energy |
| Anaerobic respiration | Aerobic respiration occurs when oxygen is low. It transfers less energy because of the incomplete oxidation of glucose. It usually occurs in muscle cells during intense exercise. Glucose --> Lactic acid (animal cells) |
| Anaerobic respiration in plant and yeast cells | Glucose --> Ethanol +Carbon dioxide In yeast cells anaerobic respiration is called fermentation and is used in the process of making bread and alcoholic drinks. |
| Exercise | During exercise the body reacts and the following occur; an increase in heart rate, an increase in breathing rate and an increase in breath volume. Together these ensure that more oxygenated blood is delivered to muscle cells for aerobic respiration to meet the increased demand for energy. |
| Anaerobic respiration in exercise | During exercise if insufficient oxygen reaches the muscles anaerobic respiration occurs The incomplete oxidation of glucose contains lactic acid Lactic acid build up leads to muscle fatigue and creates oxygen debt During exercise blood flowing through muscle transports lactic acid to the liver where it is converted back into glucose After exercise the remainder of the lactic acid in muscle cells reacts with incoming oxygen to remove it. The oxygen debt is repaid. |
| Metabolism | Metabolism is the sum of all the reactions in a cell or the body. They often require energy from respiration and are controlled by enzymes. There are two types: catabolic and anabolic |
| Respiration reaction | where energy is released from glucose |
| Synthesis reactions to form proteins | using glucose and nitrate ions to form amino acids which are then joined together to form protein |
| Photosynthesis reactions | where glucose is produced in the chloroplasts of plant and algae cells |
| Breakdown reactions to form urea | breaking down excess proteins and amino acids and then into urea for excretion from the body via the kidney |
| Synthesis reactions to form lipids | joining a glycerol molecule with three fatty acid molecules to form a lipid. Lipids form cell membranes and are an energy store |
| Synthesis reactions to form carbohydrates | converting glucose for storage in animals. converting glucose into starch in plants or cellulose for cell walls in plants |
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