2337741
Description
Flashcards by Tom Mitchell, updated more than 1 year ago
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Created by Tom Mitchell
over 9 years ago
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| Question | Answer |
| What is a population? | All the organisms of one species in a habitat |
| What is a community? | Populations of different species in a habitat |
| What is the Capture-Recapture method and what is it used for? | Capturing a small sample of the population, marking them and releasing them. Capture another sample and be able to estimate the population size by comparing the two samples. |
| What is the calculation for estimating population size? | |
| What would be the population size if 40 woodlice were captured in the first sample and 50 were captured in the second sample, of which 10 were marked? | 200 (40 x 50) / 10 |
| How does sample size affect the accuracy of the estimate? | The bigger the sample the more accurate the estimate |
| What 3 assumptions must be made whilst applying the Capture-Recapture method? | There have been no changes to the population size The sampling methods were identical The marking hasn't affected the individuals chance of survival |
| What is an ecosystem? | All the organisms living in a particular area as well as all the abiotic conitions |
| What is meant by abiotic? | Physical factors e.g. temperature, salinity, soil quality |
| What is meant by biotic? | Living factors e.g. Oganisms |
| What is the difference between a habitat and an ecosystem? | A habitat is the area where the organisms live. An ecosystem is all the factors in that area, biotic and abiotic, such as organisms and temperature |
| What does self-supporting mean? | They contain almost everything they need to maintain themselves, such as nutrients, water and essential elements |
| What is a transect? | A line across a part of a habitat |
| What are transects used for? | Finding out the distribution of organisms in a specific area |
| What is Zonation? | The gradual change in distribution of a species across a habitat |
| What 3 things is biodiversity a measure of? | The variation between individuals of the same species in an area The number of different species in an area The number of different habitats in an area |
| What is the difference between a natural and artificial ecosystem? | A natural ecosystem is able to maintain itself without any major interference from humans An artificial ecosystem is created and maintained by humans |
| What is the balanced symbol equation for photosynthesis? | |
| How many stages are there to photosynthesis? | 2 |
| Where does photosynthesis take place? | In the Chloroplasts |
| What happens in the first stage of photosynthesis? | Light energy is used to split water into oxygen gas and hydrogen ions |
| What happens in the second stage of photosynthesis? | The carbon dioxide gas combines with the hydrogen ions to make glucose and water |
| Why isn't water a product of photosynthesis? | More gets used up in the first stage than the amount produced in the second stage |
| Why do plants continuously respire? | The plants cells constantly need energy to survive |
| What two reasons are there for storing glucose as an insoluble starch? | The starch cannot dissolve in water and move away from storage areas It doesn't affect the water concentration inside the cell |
| What 5 things do plants use glucose for? | Respiration (energy) Making Cell Walls (cellulose) Stored in Seeds (lipids) Stored as Starch (used for respiration at night) Making Proteins (Amino Acids for Growth and Repair) |
| How did the Greeks think plants gained mass? | From soil minerals |
| How did Van Helmont think plants gained mass? | By taking in water |
| What did Priestley's experiments show? | That plants produce oxygen |
| What 3 factors limit the rate of photosynthesis? | Temperature Light levels Levels of carbon dioxide |
| What is diffusion? | The net movement of particles from an area of high concentration to an area of low concentration |
| Why does diffusion occur in liquids and gases? | The individual particles are free to move about randomly |
| What 3 factors affect the rate of diffusion? | Distance Concentration gradient (difference) Surface area |
| Did you know? Cell Membranes are able to let very small molecules, like simple sugars, water or ions, in and out of the cell. Big molecules like starch and proteins can't pass through. | |
| Label the diagram | |
| What mostly diffuses into the leaf during the day? What mostly diffuses out? | Oxygen diffuses out Carbon dioxide diffuses in (Due to photosynthesis exchanging gases faster than respiration) |
| What mostly diffuses into the leaf at night? What mostly diffuses out? | Oxygen diffuses in Carbon dioxide diffuses out (Due to no photosynthesis occurring, just respiration) |
| What 5 ways are leaves adapted for diffusion? | The leaves are broad meaning there is a large surface area. They are thin meaning there is only small distance for particles to diffuse. The stomata allow gases, like carbon dioxide and oxygen, in and out. Guard cells are able to control gas exchange by controlling when the stoma opens and closes. There are air spaces in the spongy mesophyll layer allowing gases to exchange between the stomata and the chloroplasts. "They have a very big internal surface area to volume ratio." |
| What 5 ways are leaves adapted to absorb light? | Being broad allows a large surface area to absorb light. Contains lots of chloroplasts, these contain a variety of photosynthetic pigments to absorb light energy. Different pigments allow for a wider variety of wavelengths to be absorbed. The cells that contain the most chloroplasts are arranged in the palisade layer near the top of the leaf. The upper epidermis is transparent so that light can pass through to the palisade layer. |
| What are the two transport vessels in plants? | Xylem and Phloem |
| What does the Phloem transport? | Food substances, mainly sugars |
| What does the Xylem transport? | Water and minerals up the plant |
| What is the use of the vascular bundle? | To deliver water and nutrients to every part of the plant and take away glucose produced in photosynthesis. It also helps to support the plant's structure. |
| How do root hairs take in water? | Osmosis |
| What is transpiration? | The loss of water from the plant |
| Describe the 3 stages of transpiration | Water vapour is lost from the leaf by evaporation and diffusion This causes a shortage of water in the leaf, resulting in water being taken by by the xylem to replace it This causes more water to be drawn from the roots, maintaining a constant transpiration stream |
| What are the 4 benefits of the transpiration stream? | The constant stream of water keeps the plant cool There is a constant supply of water for photosynthesis The water creates turgor pressure in the cells that helps to support the plant Minerals are also brought up from the soil with the water |
| What is transpiration rate affected by? | Light intensity Temperature Air movement Air humidity |
| How does light intensity affect transpiration rate? | The brighter the light, the greater the transpiration rate. Stomata close when it gets dark. Photosynthesis can't happen at night so they don't need to stay open to let carbon dioxide in. Water cannot escape when the stomata close. |
| How does temperature affect transpiration rate? | The warmer it is, the faster transpiration happens. When it's warm, the particles have more energy to evaporate and diffuse out of the stomata |
| How does air movement affect transpiration? | More wind results in a higher transpiration rate The wind moves water vapour away from the leaf, leaving a low concentration of water vapour outside the leaf that the water inside the leaf diffuses into more quickly |
| How does air humidity affect the rate of transpiration? | The dryer the air outside the leaf, the faster diffusion of water vapour can happen as the concentration is much higher in the leaf than outside |
| What 3 ways have plants adapted to reduce water loss from their leaves? | They have a waxy cuticle covering the upper epidermis that makes the leaf waterproof Most stomata are found on the lower surface of the leaf where it is darker and cooler, slowing transpiration The size and number of stomata the plant has depends on it's location. Plants in hot climates will have smaller and fewer stomata to prevent water loss |
| If a guard cell is turgid, is the stoma open or closed? | Open |
| What are the 3 main nutrients plants need? | Nitrates, phosphates & potassium |
| What does the plant need nitrates for? | Needed for making amino acids and proteins for growth and repair. |
| What does a lack of nitrates cause? | Poor growth and yellow leaves |
| What are the use of phosphates? | Needed for respiration and growth. Used to make DNA and cell membranes. |
| What does a lack of phosphates cause? | Poor root growth and discoloured leaves |
| What is potassium used for? | Helps the enzymes needed for photosynthesis and respiration. |
| What does a lack of potassium result in? | Poor flower and fruit growth Discoloured leaves |
| What other mineral is needed, in small amounts, for making chlorophyll? | Magnesium |
| What do root hairs use to take in minerals? | Active Transport |
| How does active transport work? | It uses energy from respiration to help pull minerals into the root hair |
| Why do root hairs have to use active transport? | The concentration of minerals is usually lower in the soil so using regular diffusion would cause the root hair to lose nutrients |
| What 4 things does the rate of decay depend on? | Temperature Amount of oxygen Amount of water |
| What is the result of these factors being at optimum level? | Micro-organisms are able to grow and reproduce faster, speeding up the rate of decay |
| What do detritivores feed on? | Detritus (dead and decaying material) |
| How do detritivores speed up the rate of decay? | They break up the material as they feed on it, leaving a larger surface area for smaller decomposers to work on |
| How do saprophytes feed on decaying material? | Extracellular digestion |
| What is extracellular digestion? | Secreting digestive enzymes that break down the material into smaller bits that can then be absorbed |
| What are the 6 methods used to reduce the rate of decay? | Canning Cooling Freezing Drying Adding salt/sugar Adding vinegar |
| How does canning reduce the rate of decay? | Keeps decomposers out |
| How does cooling reduce the rate of decay? | Slows the decomposer's reproduction rate |
| How does freezing reduce the rate of decay? | Decomposers can't reproduce at all |
| How does drying reduce the rate of decay? | Decomposers can't carry out reactions without water |
| How does adding salt/sugar reduce the rate of decay? | A high concentration of salt/sugar around decomposers results in the decomposer losing water by osmosis This damages them and they can't work properly |
| How does adding vinegar reduce the rate of decay? | The acidity kills the decomposers |
| What is intensive farming? | Trying to produce as much food as possible from your land, animals and plants |
| What are 4 advantages to intensive farming? | A lot of food is able to be produced from less land Huge variety of top quality foods Foods available all year round Makes prices cheaper |
| What is hydroponics? | Where plants are grown without soil |
| What are the advantages of hydroponics? | Mineral levels can be controlled more accurately Diseases can be controlled more effectively |
| What are the disadvantages of hydroponics? | Lots of fertilisers need to be added There's no soil to anchor the plants and support them |
| What are two instances where hydroponics are used? | Growing glasshouse tomatoes on a commercial scale In areas where the soil is barren |
| What is an advantage of using pesticides? | Kills creatures that damage crops |
| What are 3 disadvantages of using pesticides? | Can kill organisms that aren't pests Can cause a food shortage for animals further up the food chain Pesticides can be passed on up the food chain, killing animals further up |
| What is biological control? | Using living things to control a pest |
| What are the 2 advantages of using biological control? | No chemicals used meaning less pollution, less disruption of food chains and less risk of harm to humans There's no need to repeat the treatment, unlike with chemicals |
| What are the 4 disadvantages to biological control? | The predator may not eat the pest The predator may eat useful species The predator's population may get out of control The predator may not stay in the area where it is needed |
| What are 3 advantages to using organic farming methods? | Less chemicals used so less risk of toxins remaining on foods More environmentally friendly; less chance of polluting rivers, disrupting food chains and haring wildlife No battery farming, farm has to follow ethical guidelines |
| What are 3 disadvantages to organic farming? | Takes up more space than intensive farming More labour intensive, makes food more expensive Can't grow as much food |
| How does intensive farming reduce energy loss? | Herbicides kill weeds, giving the crops more energy from the sun and not having any competition Using pesticides kills pests, ensuring that no energy is transferred into another food chain Battery farming animals saves energy by ensuring the animals are warm and can't move about |
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