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57 Cards in this Set
- Front
- Back
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What is a habitat? |
The area in which an organism lives. |
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What is biodiversity? |
A large variety of organisms. |
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How are artificial ecosystems different from Natural ecosystems? |
There is a small biodiversity, usually only one organism in artificial ecosystems. |
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What is the capture-recapture method equation? |
Number in 1st sample x number in 2nd sample ---------------------------------------------------------------------- Number of marked organisms in 2nd sample |
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Why might the capture-recapture method be inaccurate? |
- The organisms may not die or reproduce - The organisms may not migrate - The marks may affect the survival of the organism - The organism may learn how to prevent recapture - The sampling methods may change |
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What is the balanced symbol equation for photosynthesis? |
6CO2 + 6H2O -> C6H12O6 + 6O2 |
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What are the 4 key uses of glucose in plants? |
- Converted to cellulose for cell walls - Converted to proteins for growth and repair - Converted into fats and oils for storage. - Used as energy for respiration |
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Why is starch used for storage in plants? |
- It's insoluble - It doesn't affect the water concentration of cells, causing osmosis. |
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What are the two stages of photosynthesis? |
1. Water is split up by light energy to release oxygen gas, and hydrogen ions. 2. Carbon dioxide combines with hydrogen ions. |
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What are the limiting factors of photosynthesis? |
- More Carbon Dioxide - More light - A higher temperature |
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Explain the cell structure of a leaf. |
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Which layer of the leaf contains the most chloroplasts? |
The upper palisade layer, as it will receive the most light. |
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What is special about the upper and lower epidermis? |
They contain no chloroplasts, and are therefore transparent. This means there are no barriers to light entering the leaf. |
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Why are there gaps between the spongy mesophyll cells? |
So the diffusion of gases between cells and the outside air can take place. |
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Explain 5 leaf adaptations to maximise photosynthesis. |
- Large SA - to absorb as much light as possible. - Thin - to allow light to all the cells and gases to easily diffuse through. - Chloroplasts - contain pigment chlorophyll, to absorb light energy. - Veins - to transport water and glucose. - Stomata - regulate water loss, and the flow of carbon dioxide and oxygen. |
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Define diffusion. |
The net movement of particles from an area of high to low concentration. |
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How do molecules of water, carbon dioxide and oxygen enter cells for photosynthesis? |
If there is a low concentration of a substance inside the cell, they will diffuse through the cell membrane. |
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Define Osmosis. |
The net movement of water molecules from an area of high to low concentration, through a partially permeable membrane. |
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Why do dehydrated plants wilt? |
When water is plentiful, it enters plant cells. This increases the pressure against the cell wall, and is called turgor pressure. It keeps the plant from collapse. When too much water leaves the cell, the pressure decreases and the plant wilts. |
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What do you call a plant cell filled with water? |
Turgid. |
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What is plasmolysis? |
The shrinking of a plant cell due to water loss. The cell membrane pulls away from the cell wall. The cell is described as flaccid. |
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What happens to an animal cell when too much water enters? |
They swell and burst. This is called lysis. |
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What happens to an animal cell when too much water leaves? |
It shrinks into a scalloped shape. This is called crenation. |
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Describe the features of xylem. |
They are dead, with hollow lumen. They're reinforced with lignin to support the plant. |
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What is the purpose of xylem? |
Xylem carry water and minerals from the roots to the leaves. |
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What is the purpose of Phloem? |
Phloem carry food substances, such as glucose, around the plant. This is called translocation. |
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Explain the Transpiration Cycle. |
Water is absorbed by root hair cells, then transported to leaves through xylem. It then diffuses and evaporates - leaving the plant from inside leaves. |
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Why do plants need water? |
- To cool the plant (when evaporating) - Photosynthesis - To keep the plant from wilting - The transport of minerals |
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What factors increase the rate of transpiration? |
- Increase in light intensity - open stomata - Increase of temperature - increase evaporation - Increase in air movement (wind) - blowing away humid air - Low humidity - increase evaporation |
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What adaptations prevent water loss from a leaf? |
- Waxy Cuticle - Guard Cells - Stomata being mostly located on the lower side of leaf |
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How do guard cells work? |
When there is plenty of water, there is a lot of glucose produced. This makes the guard cells go turgid, opening the stomata and allowing excess water out. In dry conditions, photosynthesis decreases and the guard cells go flaccid, closing the stomata. |
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Why do plants need nitrogen and what happens in they have a nitrogen deficiency? |
Nitrogen (nitrates) help make a variety of amino acids (proteins) for cell growth. Nitrogen deficiency causes yellow leaves and poor growth. |
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Why do plants need phosphorus and what happens in they have a phosphorus deficiency? |
Phosphorus (phosphates) - make DNA and cell membranes. Phosphorus deficiency causes poor root growth and discoloured leaves. |
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Why do plants need potassium and what happens in they have a potassium deficiency? |
Potassium (potassium compounds) aid enzyme action. Enzymes are speed up chemical reactions (respiration and photosynthesis). Potassium deficiency causes poor flower & root growth, and discoloured leaves. |
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Why do plants need magnesium and what happens in they have a magnesium deficiency? |
Magnesium (magnesium compounds) make chlorophyll, which is essential for photosynthesis. Magnesium deficiency causes yellow leaves. |
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Define Active Transport. |
Root Hair Cells use energy to transport substances through cell membranes against a concentration gradient (from low to high). It is used to absorb minerals. |
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Define Detritus. |
Dead or decaying matter. |
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What are detrivores? |
Organisms, such as worms and woodlice, that feed on detritus. They increase the rate of decay by breaking up the detritus and increasing the surface area for further breakdown (by decomposers) |
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Why does oxygen increase the rate of decay? |
Bacteria need oxygen to respire, and will grow and reproduce quicker with more oxygen present. |
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What is a decomposer? |
An organism, such as bacteria and fungi, that releases enzymes to break down organic matter. |
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How does temperature increase the rate of decay? |
Higher temperature will increase the rate of respiration of decomposers. However, at a certain temperature (25 for fungi and 37 for bacteria), the enzymes will denature. |
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How does water increase the rate of decay? |
Water allows materials to be digested and absorbed more efficiently; increases growth; and increase reproduction of fungi and bacteria. |
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How does canning prevent decay? |
Foods are heated to destroy bacteria, and then sealed in a vacuum and to prevent the entry of oxygen and bacteria. |
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How does freezing reduce the rate of decay? |
The low temperatures will kill some bacteria and slow growth and reproduction. |
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How does cooling reduce the rate of decay? |
Low temperatures will slow bacterial and fungal growth. |
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How does drying foods prevent decay? |
It removes water, so bacteria cannot feed and grow. |
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How does salting/sugaring foods reduce the rate of decay? |
The high osmotic concentration will remove water from fungi and bacteria. |
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How does vinegar prevent decay? |
Acidic conditions will kill most fungi and bacteria. |
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Why do insecticides, pesticides and herbicides cause problems? |
- They can accumulate in food chains, until they become lethal for predators. - They take a long time to break down. - They can harm other organisms that are not pests. |
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Explain the key features of organic farming. |
- They don't use any chemicals, including pesticides and antibiotics. - Manure and compost; crop rotation; and nitrogen-fixing plants are used to get the best possible crops. |
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What are the advantages and disadvantages of organic farming? |
Advantages - ethical; reduces health risks. Disadvantages - less produce; more expensive. |
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Define Biological Control. |
The use of living organisms to control pests, for example ladybirds eat crop-damaging aphids. |
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What are the advantages and disadvantages of biological control? |
Advantages - avoid disadvantages of artificial pesticides; don't need replacing. Disadvantages - damage food chains; increase of population until thy become pests. |
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Define Intensive Farming. |
A form of farming that produces high produce yields in small spaces using pesticides and antibiotics. |
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What are the advantages and disadvantages of Intensive Farming? |
Advantages - cheap; produces large yields; improved energy efficiency. Disadvantages - raise concerns for animal cruelty; disadvantages of pesticides; antibiotics are used throughout animal lifetimes causing human bodies to become immune to antibiotics. |
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Define Hydroponics. |
A closed system using recycled aerated water that contains the perfect amount of minerals for growth and production. It is a form of intensive farming. |
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What are the advantages of Hydroponic farming? |
- It doesn't use much space - Once set up, it is cheap to maintain as all materials are recycled. - Fertilisers don't damage environment as it is a closed system. |
