Transport in plants and humans
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- Created by: Jan Shah
- Created on: 12-04-13 15:52
What is diffusion?
Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration down a concentration gradient.
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What is osmosis.
Osmosis is the movement of water molecules from high water potential to low water potential across a semi-permeable membrane.
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Why does an animal cell become lysed?
This is when there is too much water moving into the cell as there is a higher concentration of water outside the cell.
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Why does an animal cell become shrivelled?
It happens when too much water moves out of the cell as there is a higher concentration of water inside the cell than outside.
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hWhy does a plant cell become turgid?
It happens when too much water goes into the cell. As a result of this the cell walls become hard but do not burst. This is because the concentration of water is highest outside the cell than inside so the water goes in.
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Why does a plant cell become plasmolysed?
This is because too much water is moving out of the cell so the cytoplasm pulls away from the cell wall. This is because the water concentration is highest inside the cell than outside.
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What is the function of a leaf?
The function of a leaf is to make food (sugars) for the plant using photosynthesis. The leaf needs energy (from sunlight), water (from the soil) and carbon dioxide (from the atmosphere).
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How is structure of leaf adapted for gas exchange?
They have long, thin shapes gives the leaf a very large surface area, air spaces between cells allow carbon dioxide/oxygen to diffuse away from the photosynthetic cells, Stomata to allow carbon dioxide to diffuse in and oxygen to diffuse out the leaf
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What are the stomata?
Stomata are holes formed inbetween two guard cells.
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What is the top layer of the leaf called and what does it do?
The upper epidermis. It protects the leaf from harmful organisms and maintains structure.
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What do the palisade cells do?
It is to abosrb sunlight for photosynthesis to produce food for the plants.
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What does the spongy mesophyll cells?
It allows gases to circulate through the numerous spaces and for photosynthesis.
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What do the guard cells do?
These allow the exchange of gases and to open and close the stomata.
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What is the bottom layer of the leaf called and what does it do?
The lower epidermis helps to protect and provides structure to the leaf.
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List the reasons why plants need water.
To produce chemical reactions inside the cell, to allow the cell to become turgid, 70% of the cytoplasm in the cell is water, it is used for photosynthesis, for the cells to function, transport of nutrients, so that the plant remains upright and cool
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How is water always being lost?
Water is always being lost by evaporation - this creates a pulling force (negative pressure) that literally sucks water up through the plant.
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What is the process by which water travels through a plant?
Transpiration.
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Why is the loss of water from leaves inevitable?
The loss of water is inevitable because the stomata must always be open to allow CO2 into the leaf for photosynthesis. As there is a higher concentration of water inside the cell than outside the water molecules will always diffuse out through stomat
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Describe the 2-step process of transpiration.
Liquid water eveporates from the mesophyll cells into the air spaces using energy from sunlight then the water vapour diffuses out through the open stomata down a concentration gradient.
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What is transpiration?
It is the loss of water from the leaves by evaporation and diffusion.
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How is water transported through the plant?
It is transported from the roots to the leaves by specialised vessels called xylem cells.
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How is water absorbed?
Water is absorbed from the roots by specialised cells called root hair cells.
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What are the structural features of the xylem cell and how do they improve water transport?
They have no cell content as it allows the water to move faster because there is nothing to resist the flow of water, the end walls between cells break down since this forms a continous tube allowing the water to move faster.
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What are the structural features of the xylem cell and how do they improve water transport?
The cell walls fill with lignin to make them waterproof and supports them to stop them from collapsing.
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What is function of a root hair cell?
It is to absorb water by osmosis and mineral ions by active transport.
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What are the structural features of the root hair cell and how does it improve absorption?
It has a long, thin projection of the root hair which creates a bigger surface area so that it does diffusion, osmosis and active transport faster, it has a thin cell wall which creates a shorter distance for water to travel into the cell.
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What are the structural features of the root hair cell and how does it improve absorption?
It has mitochondria and transport protein which provides energy for active transport and transports ions against the concetration gradient.
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How does the water moves across the cells?
There is a concetration gradient across the cells, so water moves by osmosis from a cell with a higher concentration to cells with a lower concentration of water across a semi-permeable membranne.
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What are plants which are adapted to dry conditions called?
Xerophytes
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How is a cactus adapted to reduce water loss?
There leaves are reduced to spines which means that there is a smaller surface area for evaporation, it also has a succulent stem which stores water and it has shallow roots spread over a large area which allows the cactus to absorb any quick rainfal
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How is marram grass adapted to reduce water loss?
It leaves curl over which reduces surface area for evaporation and it has epidermal hairs which traps layers of humid air outside the stomata reducing the concentration gradient.
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What is the evaporation, concentration gradient and rate of transpiration like when there is increased wind speed?
The evaporation remains unchanges, the concentration gradient becomes steeper as the wind removes the water vapour so the concentration of water outside decreases and the rate of transpiration increases.
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What is the evaporation, concentration gradient and rate of transpiration like when there is increased humidity?
The evaporation remains unchanged, the concentration gradient becomes less steep as there is increased concentration of water outside in the air and the rate of transpiration decreases.
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What is the evaporation, concentration gradient and rate of transpiration like when there is increased temperature?
The evaporation increases, the concetration gradient becomes steeper as there is more evaporation and there is an increased amount of water molecules inside the leaf and the rate of transpiration increases.
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What is the specialised vessel used to transport water and sugars?
Phloem
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How is the phloem adapted to improve transport?
It has reduced cell content which means there is less resistance to the flow of organic molecules and it has holes in the end walls which allow molecules to move more easily from one cell to another.
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How are the sugars loaded into the phloem?
By active transport.
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What is used to measure the rate of transpiration?
Potometer
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How many chambers does the heart contain and what are they?
It contains 4 chambers which are the right atrium and ventricle and the left atrium and ventricle.
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In the heart what does the deoxygenated blood enter and through what?
It enters the right atrium through the vena cava.
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In the heart how does the deoxygenated blood leave?
It leaves from the right ventricle through the pulmonary artery on its way to the lungs.
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Where does the oxygenated blood enter and through what?
It enters the left atrium through the pulmonary vein.
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How does the oxygenated blood leave the heart?
It leaves from the left ventricle through the aorta to the rest of the body.
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What does the bicuspid valve do?
It prevents backflow from the left ventricle to the left atrium.
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What does the tricuspid valve do?
It prevents backflow from the right ventricle to the right atrium.
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What do the semi-lunar valves do?
They prevents the backflow from the ventricles.
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What is coronary heart disease?
Coronary heart disease is when fatty deposits build up in the coronary artery which blocks it. This prevents the oxygen from reaching the muscles in the heart therefore the heart stops beating.
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What do phagocytes do?
Phagocytes engulf the pathogen and breaks it down.
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What do lymphocytes do?
They creates antibodies which recognises the antigens on a pathogen.
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Other cards in this set
Card 2
Front
What is osmosis.
Back
Osmosis is the movement of water molecules from high water potential to low water potential across a semi-permeable membrane.
Card 3
Front
Why does an animal cell become lysed?
Back
Card 4
Front
Why does an animal cell become shrivelled?
Back
Card 5
Front
hWhy does a plant cell become turgid?
Back
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