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Science B2 Topic 2
GCSE edexcel additional science biology: organisms and energy
| Question | Answer |
|---|---|
| What is respiration? | A process used by all living organisms that releases energy in the form of organic molecules that are needed to carry out life processes |
| What is the word equation for aerobic respiration? | Glucose + oxygen --> carbon dioxide + water |
| What is diffusion? | A spontaneous process where particles of a substance move from an area of high concentration to an area of low concentration- they diffuse down a concentration gradient. |
| What is gas exchange? | Where oxygen diffuses through the alveoli in the lungs and into the blood stream, and carbon dioxide does the opposite to get out of the body |
| How are capillary walls and alveoli adapted to their function in diffusion? | They are both one cell thick so that substances can diffuse across them quickly and easily |
| What increases with exercise and why? | The rate of respiration: the breathing rate increases to get more oxygen into the blood, and the heart rate increases so more blood gets to cells |
| What is cardiac output and how is it calculated? | It is the volume of blood circulated by the heart. Cardiac output = stroke volume x heart rate |
| What is stroke volume? | The volume of blood pumped out of the blood on each beat |
| Why might anaerobic respiration occur? | During vigorous exercise, muscle cells may not receive sufficient oxygen for their energy requirements, so an alternative process called anaerobic respiration occurs alongside aerobic respiration |
| What is the word equation for anaerobic respiration? | Glucose --> lactic acid |
| What are some disadvantages of anaerobic respiration? | Produces lactic acid which is toxic in high concentrations and causes cramping of muscles, and it releases less energy than aerobic respiration |
| What is EPOC? | Excess post-exercise oxygen consumption is the volume of oxygen required after exercise to break down the lactic acid. Lactic acid + oxygen --> carbon dioxide + water. breathing rate & heart rate remain high after exercise to distribute oxygen |
| What is the recovery time? | The time taken for pulse rate to return to the resting rate after exercise |
| What is photosynthesis? | A series of enzyme-catalysed reactions in plant cell organelles called chloroplasts by which plants manufacture their own food using sunlight |
| What is the word equation for photosynthesis? | Carbon dioxide + water --> oxygen + glucose |
| What is chlorophyll? | Chlorophyll is a green pigment found in chloroplasts which absorbs light and transfers light energy into stored chemical energy in glucose |
| How is the structure of a leaf adapted for photosynthesis? | * large surface area to absorb lots of light energy * stomata open in response to light + allow gas exchange * chloroplasts contain chlorophyll to absorb light energy * air spaces inside leaf give cells a large area to volume ratio for gas exchange |
| What are some limiting factors for photosynthesis? | * light intensity * carbon dioxide concentration * temperature- too cold = rate decreases. too hot = denatured enzymes (i.e. there is an optimum temperature for enzymes where photosynthesis happens fastest) |
| What is meant by a limiting factor for photosynthesis? | If one of the three factors are limited, then photosynthesis can't occur at a fast rate, even if the other two factors are in abundance |
| How are roots adapted to their function? | They have root hair cells on them that increase the surface area of the root to increase the volume of water and nutrients that are absorbed |
| How does water enter root hair cells? | By osmosis - a type of diffusion whereby water moves across a partially permeable membrane from a region where water is in higher concentration to where it is in a lower concentration |
| What is xylem tissue and what is its function? | Xylem tissue consists of long cells that die and form hollow tubes. The tubes give support to the plant and transport water and nutrients to tissues |
| What is transpiration? | water evaporates from a leaf by diffusion when the stomata are open, maintaining a concentration gradient, so more water diffuses out of the leaf. The loss of water from the leaf pulls water and mineral salts up through the xylem from the roots |
| What are the names for limp and inflated cells? | Flaccid = a plant cell that is limp Turgid = a plant cell fully inflated with water |
| What is phloem tissue and what is its function? | Phloem is involved in translocation of food substances from stems to growing and storage tissues. consists of living cells in columns. Glucose made by photosynthesis is converted to sucrose and is carried by phloem tissue to other parts of the plant |
| What is active transport? | Active transport is the process by which dissolved molecules move across a membrane from a lower concentration of the solute to a higher concentration of the solute. This requires energy as it moves against the concentration gradient. |
| When is active transport used? | To absorb mineral ions dissolved in the soil water even if the concentration of the ions is higher inside the roots |
| What is biodiversity? | The variety of species of animals and plants in an ecosystem or habitat |
| What is sampling? | Sampling is looking at a small portion of an area or a population |
| What is random sampling? | Every point within an area has an equal chance of being selected - the data will probably be representative |
| What is systematic sampling? | Taking samples at regular intervals along a line |
| What are some sampling techniques? | Pooter catches small invertebrates through an inlet tube by sucking sharply on a 2nd tube. Sweep net catches organisms in long grass. Pond net catches organisms in water. Pitfall trap catches small animals (spiders. Quadrats sample the number of organisms |
| How do you measure environmental factors? | A light intensity meter measures light intensity. A pH probe measures pH. A temperature probe measures temperature |
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