Flashcards
B4
Flashcards do conjunto (80)
- 1What is photosynthesis?The process that uses the Suns energy to change carbon dioxide and water into glucose and oxygen
- 2Where does photosynthesis occur?In chloroplasts in plant cells- they contain pigments like chlorophyll that absorb light energy.
- 3What is the balanced equation for photosynthesis?
- 4What is the first stage of photosynthesis?Light energy is used to split water into oxygen gas and hydrogen ions
- 5What is the second stage of photosynthesis?Carbon dioxide gas then combines with the hydrogen ions to make glucose and water. Water is NOT an end product as more is used in the first stage than is made in the second stage
- 6How do plants use glucose for respiration?It releases energy so they can convert the rest of the glucose into various other useful substances
- 7How do plants use glucose for cell walls?Glucose is converted into cellulose for making cell walls, especially in a rapidly growing plant
- 8How do plants use glucose for storing in seeds?Glucose is turned into lipids (fats and oils) for storing in seeds. Sunflower seeds, for example, contain a lot of oil- we get cooking oil and margarine from them.
- 9How do plants use glucose forsaking as starch?Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn't happening, like at night.
- 10How do plants use glucose for making proteins?Glucose is combined with nitrates (collected from the soil) to make amino acids, which are then made into proteins. these are used for growth and repair.
- 11Why is starch good for storing?It is insoluble slit can't dissolve in water and move away from storage areas in solution. Also, it doesn't affect the water concentration inside cells- soluble substances would bloat the storage cells by drawing in water.
- 12What did Greek scientists conclude about plants?They realised the only thing touching plants was soil so they must get their minerals and nutrients to grow and gain mass form the soil.
- 13What was Jan van Helmont's experiment about plants?He set up the flowing experiment: he dried some soil, weighed it and then planted a 2.2kg willow tree in it. After 5 years the tree weighed 76.7 kg so he concluded that it gained mass form the water as the soil lost no mass. Today we know that mass is also gained from co2.
- 14What was Joseph Priestley's first experiment?He placed a burning candle in a sealed container and it quickly went out. He placed a candle in another sealed container with a living plant and it went out quickly again but could be re lit with in a few weeks. He concluded the plant restored the air (released oxygen)
- 15What was Priestley's second experiment?He filled a sealed container with exhaled air (co2) and put a mouse in it that died quickly. He out a living plant in the container and waited a few days. The mouse lived longer (a few minutes). Again he concluded that the plant restored the a with oxygen.
- 16Where does the oxygen produced in photosynthesis come from?Water, NOT CARBON DIOXIDE
- 17What are the three limiting factors that control the rate of photosynthesis?Light, carbon dioxide and temperature
- 18How does light affect the rate of photosynthesis?Light provides the energy needed for photosynthesis. If the light level is raised, the rate of photosynthesis will increase, but on,y up to a certain point. This point is when either carbon dioxide or temperature become the limiting factor.
- 19How does carbon dioxide affect the rate of photosynthesis?Too little carbon dioxide slows down the rate of photosynthesis. Carbon dioxide is one of the raw materials needed for photosynthesis. As co2 increase, the rate increases until there is a new limiting factor (temperature or light).
- 20How does temperature affect the rate of photosynthesis?Photosynthesis works best when it is warm but not too hot. As the temperature increases, so does the rate, until there is a new limiting factor. If it is too hit the plants enzymes are denatured and the rate rapidly decreases (usually 45 degrees). If temperature is the limiting factor it is normally because it is too low.
- 21What is diffusion?The gradual movement of particles from places where there are lots of them to places where there are fewer of them.
A net movement of particles form an area of high concentration to an area of lower concentration. - 22Where does diffusion occur?Liquids and gases- the individual particles in these substances are free t move around randomly. The simplest type is when different gases diffuse through each other. This is what is happening when the smell of a perfume diffuses through the air in a room.
- 23How are cell membranes useful in diffusion?They let stuff in and out. Only very small molecules can diffuse through the cell membranes though, like simple sugars, water or ions. Big molecules like starch and proteins can't pass through the membrane.
- 24What three things does the rate of diffusion depend on?Distance- substances diffuse faster when they don't have as far to move
Concentration difference (gradient)- substances diffuse faster if it is a big difference in concentration.
Surface area- the more surface area, the faster the rate - 25Labelled diagram of a leaf cross-section
- 26What two opposite processes to plants carry out?Photosynthesis (energy required) and respiration (energy released)
- 27When does hoot synthesis occur?During the day when there is light
- 28When does respiration occur?All the time to get the energy they need to leave.
- 29What do plants do in the day? And at night?During the day, plants make more oxygen by photosynthesis than they use in respiration. In daylight, they release oxygen and take in carbon dioxide. At night plants only respire as there is no light for photosynthesis. This means they take in oxygen and release carbon dioxide.
- 30Diffusion during photosynthesisDuring photosynthesis, lots of carbon dioxide is used up and there is little in the leaf. This means more diffuses into the leaf (from high to low concentration). At the same time oxygen is being made as a waste product of photosynthesis. Some is used in respiration and the rest diffuses out of the leaf to lower concentration.
- 31Diffusion during respirationAt night there is no light for photosynthesis so lots of carbon dioxide is made in respiration and lots of oxygen is used up. There's a lot of carbon dioxide in the leaf and not much oxygen so now it is mainly carbon dioxide diffusing out and oxygen diffusing in.
- 32How are leaves adapted for efficient photosynthesis?Broad, thin, have stomata, have guard cells, and have air spaces
- 33How is being broad an adaptation?There is a large surface area for gases to diffuse over
- 34How is being thin an adaptation?Carbon dioxide and water vapour only have to diffuse a short distance to reach photosynthesising cells where they are needed.
- 35How is having stomata an adaptation?The lower surface is full of little holes called stomata. They're there to let gases like CO2 and O2 in and out. They also allow water to escape, which is known as transpiration.
- 36How is having guard cells an adaptation?Leaves have guard cells surrounding each stoma to control when the stoma opens and closes. This lets the guard cells control gas exchange.
- 37How is having air spaces an adaptation?There are air spaces in the spongy mesophyll layer. This allows gases like CO2 and O2 to move between the stomata and the photosynthesising cells. This also means there is a large surface area for gas exchange ( a big internal surface area to volume ratio)
- 38How are leaves adapted to absorb light?Broad, have chloroplasts and have different pigments
- 39How is being broad an adaptation?There is a large surface area exposed to light
- 40How is having chloroplasts an adaptation?Chloroplasts contain chlorophyll and other photosynthetic pigments to absorb light energy
- 41How is having different pigments an adaption?Different pigments absorb different wavelengths of light, so plant cells can make the most of the suns energy by absorbing as much of it as possible.
- 42Pigments found in plants and the wavelengths they absorb...
- 43Where are the cells containing the most chloroplasts arranged?In the palisade layer near the top of the leaf where they can get the most light
- 44How is the upper epidermis adapted?It is transparent so light ca easily pass through it to the palisade layer
- 45Why do leaves have a network of vascular bundles?The vascular bundles are the transport vessels, xylem and phloem. They deliver water and other nutrients to every part if the leaf and take away the glucose produced by photosynthesis. They also help support the leaf structure.
- 46What is osmosis?The net movement of water molecules across a partially permeable membrane from a region of higher water concentration (dilute solution) to a region of lower water concentration (concentrated solution)
- 47What is a partially permeable membrane?One with very small holes in it, so only tiny molecules like water can pass through them, and bigger molecules like sucrose can't
- 48What direction do the water molecules pass through the membrane?Both ways because the water molecules move about randomly all the time.
- 49Where does the steady net flow occur and why?The region into the stronger sucrose solution (less water) because there are more water molecules on the other side
- 50What happens to the concentrated sucrose solution as a result?It gets more dilute- the water tries to even out the concentration on both sides of the membrane
- 51What is meant by Turgid?When a plant is well watered its cells will draw water in by osmosis and become plump and swollen. When the cells are like this they are said to be turgid.
- 52What is turgor pressure?When the contents of the cell push against the inelastic cell wall. Turgor pressure helps support the plant tissues
- 53What happens when a plant doesn't have enough water from the soil?The plant starts to wilt because ethe Ella start to lose water and so lose their turgor pressure. They're then said to be flaccid
- 54What is a plasmolysed cell?If the plant is really short of water, the cytoplasm inside it shrinks and the membrane pulls away from the cell wall. The cell is now said to be plasmolysed. The plant does not totally lose its shoe though, as the inelastic walk keeps things in position.
- 55What happens if an animal cell takes in too much water?The cell will burst as it down at have a cell wall. This is known as lysis
- 56What happens if an animal cell loses too much water?The cell shrivels up- this is known as crenation
- 57What do phloem tubes transport?Food substances, mainly sugars, both up and down the stem to growing and storage tissues
- 58What is translocation?The movement of food substances around the plant
- 59What are phloems made of?Columns of living cells with perforated end plates to allow stuff to flow through
- 60What do xylem tubes transport?Water and minerals from the roots up the shoot to the leaves in the transpiration stream
- 61What are the xylems walls made of and why?The thick side walls are made of cellulose. They're strong and stiff which gives the plant support
- 62What is a xylem tube made of?Dead cells joined end to end with no end walls between them and a lumen (hole) down the middle
- 63Why do things decay?because of microorganisms
- 64what are the three things rate of decay depends on?temperature, amount of water and amount of oxygen
- 65how does temperature affect rate of decay?a warm temperature makes things decay faster because it speeds up respiration in microorganisms.
- 66how does amount of water affect rate of decay?things decay faster when they're moist as microorganisms need water
- 67how does amount of oxygen affect rate of decay?decay is faster when there is oxygen available. The microorganisms can respire aerobically, providing more energy.
- 68what are detritivores?they feed on dead and decaying material (detritus). As they feed on the decaying material, they break it up into smaller bits. This gives a bigger surface area for smaller decomposers to work on and speeds up decay.
- 69what is an example of a detritivore?earthworms, maggots and woodlice
- 70what are saprophytes?they also fee on decaying material but do so by extra-cellular digestion, ie. they feed by secreting digestive enzymes on to the material outside of their cells. The enzymes break down the material into smaller bits, which can then be absorbed by the saprophyte.
- 71what is an example of a saprophyte?fungi
- 72what are the ways of preserving food?canning, cooling, freezing, drying, adding salt/sugar, and adding vinegar
- 73how does canning preserve food?it keeps decomposers out
- 74how does cooling preserve food?it slows down decay as it slows down the reproduction of microorganisms
- 75how does freezing preserve food?the decomposers cant reproduce at such low temperatures
- 76how does drying preserve food?dried food lasts longer because decomposers need water to carry out cell reactions.
- 77how does adding salt/sugar preserve food?if there's a high concentration of salt/ sugar around decomposers, they'll lose water by osmosis. This damages them and means they cant work properly.
- 78how does adding vinegar preserve food?vinegar is acidic and the acid kills the decomposers.
- 79What is lysis?Animal cells have no elastic cell wall as they don't have a cell wall. If the cell takes in too much water it burts. This is known as lysis
- 80What is crenation?If the animal cell loses too much water it gets all shrivelled up. This is known as crenation
Informações
- Descrição
- AS - Level Biology FlashCards sobre B4, criado por vittoria howard em 10-02-2015.
- Criado por
- vittoria howard · fev 2015
- Atualizado
- 6 abr 2018
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