Biology B2.2 : Organisms in the environment

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  • Created by: TillyF
  • Created on: 19-12-16 05:42
How do plants and algae make their food?
Through photosynthesis
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What do plants and algae photosynthesise for?
For respiration, growth and reproduction
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What is the word equation for photosynthesis?
carbon dioxide + water ----> (+light energy) glucose + oxygen
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Where are chloroplasts found?
Chloroplasts are the small green parts found in the cells of the algae and the leaves of the plants. They contain a green substance called chlorophyll.
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Explain what happens during photosynthesis? -mention chlorophyll/glucose/oxygen
-Light energy is absorbed by chlorophyll in the chloroplasts -the energy is used to convert CO2 from the air and water from the soil into glucose -oxygen is produced as a by-product -oxygen is the gas that we breath in
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What happens to the glucose produced during photosynthesis?
-the glucose is used immediately by the cells of the plant -some glucose is converted into insoluble starch and stored
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How can be test that photosynthesis has taken place?
Iodine solution is a yellow-brown liquid that turns dark blue when it reacts with starch. This can be used to test if photosynthesis has taken place as starch is created and stored in the plant as a result of photosynthesis
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List some adaptations of a leaf? Explain each one.
-broad leaves: large surface area for light to fall on -chlorophyll in the chloroplasts: absorb light energy -air spaces: allow CO2 to get into the cells, and oxygen to leave by diffusion -veins: bring plenty of water to the cells of the leaves
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What is an adaptation of aquatic algae?
-They absorb CO2 dissolved in the water around them, since they must photosynthesise in water
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What does a plant need in order to photosynthesise quickly?
-Carbon dioxide -Warmth -light
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What is a limiting factor?
A factor that may limit the amount of photosynthesis a plant can manage, this occurs when factors such as temperature/CO2 levels and warm temperatures are limited
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How does light effect the rate of photosynthesis?
If there is plenty of light, lots of photosynthesis can take place. If there is little or no light, photosynthesis will stop. It doesn't matter what the other conditions are like around the plant. The brighter the light, the faster photosynthesis.
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Describe the graph for the relationship between light intensity and rate of photosynthesis?
Rate of photosynthesis increases as light intensity increases, shows that light intensity is a limiting factor. Graph levels off at maximum point of rate of photosynthesis as light is no longer a limiting factor, another factor limits photosynthesis
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How can we tell that photosynthesis is taking place when a plant is in water?
Bubbles of oxygen gas are produced as a result of photosynthesis
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Why does the graph of light intensity and rate of photosynthesis level off?
The rate of photosynthesis reaches its peak no matter how bright the light and the graph levels off. This is due to another factor limiting the rate of photosynthesis, therefore preventing the rate of photosynthesis from increasing further.
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What is the relationship between temperature and the rate of photosynthesis?
Temperature affects photosynthesis, as temperature rises the rate of photosynthesis increases, as the reaction speeds up. Photosynthesis is controlled by enzymes, the enzymes denature when the temperature is too high,rate of photosynthesis will fall.
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How does carbon dioxide affect the rate of photosynthesis?
Carbon dioxide is needed for photosynthesis, carbon dioxide often limits the rate of photosynthesis as the atmosphere obtains small amounts of photosynthesis. Increasing CO2 increases the rate of photosynthesis.
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When are CO2 levels lowest and highest?
On a sunny day CO2 levels are usually limited and usually increase at night. This is because plants respire at night and don't photosynthesis, when light levels rise and temperature increases in the morning, CO2 is used up.
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How do green houses and labs control photosynthesis?
In a science lab or greenhouse CO2 levels are controlled artificially, so CO2 levels are no longer limiting and the rate of photosynthesis increases with the rise of CO2.
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List a use of glucose? (respiration)
Plants and algal cells respire constantly, they use glucose produced using photosynthesis as they respire. The glucose is broken down using oxygen to provide energy for the cells. Water and CO2 are waste products of the reaction.
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What is the energy from respiration used for?
The energy is used to build up smaller molecules into bigger molecules. Some of the glucose is changed into starch for storage, or into cellulose used to strengthen the cell walls.
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Give a way that plants use glucose? (AA)
Plants use glucose to make amino acids, this is by combining sugars with nitrate ions and other mineral ions from the soil. The amino acids are built up into protein to be used in the cells, using energy from respiration.
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How do algae make amino acids?
Through taking nitrate and mineral ions from the water that they live in.
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How do plants and algae use glucose from photosynthesis and energy from respiration? (f and o)
Fats and oils are built up, these are used for a cell as an energy store. They are sometimes used in the cell walls to make them stronger, or as an energy store in their seeds for new plants as they germinate.
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What could the oils from algal cells be used for in the future?
The fats and oils from the algal cells could be considered as a possible source of biofuels in the future.
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How does food from photosynthesis move through the plant?
Through the phloem.
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What do plants convert some of their glucose into? Why would they do this?
Plants convert some of their glucose into starch for storage, glucose is soluble in water and if it were stored in plant cells it could affects the water balance in the plant and the movement of water in and out of the cells.
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Why do we convert soluble glucose into insoluble starch?
Starch is insoluble in water so it will have no effect on the water balance of the plant so large amounts of starch can be stored in the cells.
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What is the main energy store of the plant?
The main energy store in plants is starch and is found all over the plant, stores in the cells of the leaves. Starch provides an energy store for when it is dark or when light levels are low.
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How do plants sometimes store their starch?
Insoluble starch is kept in special storage areas, they produce tubers and bulbs, helping them survive the winter, full of starch. We eat these starch stores, eg. potatoes and onions
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Why is it important for photosynthesis to be fast?
More photosynthesis, means more biomass and the faster it grows, making more profit for farmers.
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How does a green house affect the rate of photosynthesis?
Within the glass or plastic structures the environment is more controllable, the temperature is warmer inside than out, speeding up the rate of photosynthesis. This allows us to grow plants that cannot grow in colder temperatures.
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Why is it easier to grow a plant in a lab?
In a lab you can change one factor at a time while keeping others constant, you can judge how each one limits photosynthesis. Whilst outside there are a number of different factors that could affect the plants photosynthesis.
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Describe the limitations of photosynthesis in the early morning?
Light levels and temperature levels limit the rate of photosynthesis, as they rise later on in the day carbon dioxide levels are limited.
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What is hydroponics?
Hydroponics is when plants are grown in water with a perfect balance of mineral ions instead of soil so nothing slows their growth.
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What are some advantages and disadvantages of mass growing plants in a green house?
disadvantages: expensive to control environment/ a lot of energy needed advantages: turnover is fast - profits are high, crops are clean and unspoilt, no ploughing or preparing of land, fewer staff needed and monitoring systems and alarms are placed
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How does temperature affect living organisms?
Temperature limits photosynthesis and therefore growth in plants, in cold climates temperature is always limiting. Arctic plants are small and this affects the numbers of herbivores that can survive in the areas.
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How do the nutrients available affect the distribution of plants?
The level of mineral ions (nitrates) has a big impact on the distribution of plants. The venus fly trap thrive in low nitrate levels as they can trap and digest animal prey. The nitrates they need are provided when they break down animal protein.
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How do light levels affect the distribution of organisms?
Light limits photosynthesis so it affects the distribution of plants and animals. Some plants are adapted to living in low light levels, they may have more chlorophyll or bigger leaves, but most plants need plenty of light to grow.
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How does the availability of water affect the distribution of water?
Plant and animals need water to survive, that is why deserts have very few species. When it rains in the desert a large number of plants grow, flower and set seeds grow when water is available, they are eaten and taken advantage of by desert animals
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How do oxygen levels affect the distribution of organisms?
Oxygen levels in water affects aqueous organisms. Some invertebrates can survive water with low levels of O2. But most organisms need a high level of dissolved oxygen in their water, land organisms are unaffected by this as there is plenty of oxygen
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How do carbon dioxide levels affect the distribution of organisms?
Carbon dioxide levels limit the rate of photosynthesis and plant growth. In areas with lots of CO2 plants are vulnerable to more insect attacks (mosquito's), mosquitos prefer animal blood with more CO2 in as well.
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Do the physical factors that affect the distribution of organisms work in isolation?
No, physical factors interact with one another to create unique environments where different animals and plants can live.
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What is a quadrate and what does it do?
A quadrate is a square frame that outlines a sample area, they are used to sample an area (count organisms in an area). They can investigate the size of a population of plants, they can be used for stationary or slow moving animals
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How can we make our data more valid? Why is sample size important?
We can make our data more valid by sampling as many areas as possible. We need a big sample size to make sure that we have a good set of data for the area that can draw a correct conclusion on the distribution of organisms.
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Why should sample areas be random?
Random sampling ensures that your results reflect a true distribution of the organisms, making your findings valid. We can make our samples random by using a random number generator to generate co-ordinates.
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Why do we use quantitive sampling?
To compare the distribution of the same organisms in different habitats, to compare the variety of organisms in a number of different habitats.
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How do we calculate the mean? What is the median? The range? The mode?
We add the values together and divide it by the number of values. The median is the middle value of the data. The range is the range between the minimum and maximum values. Mode: Most frequent occurring value
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How else can we use sampling?
To measure the changes in distribution of organisms over time by repeating the measurements at regular time intervals.
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What is counting along a transect?
A method of measuring the distribution of organisms, it is not random, you stretch a tape between 2 points and sample the organisms along the line at regular intervals using a quadrate, showing how the distribution of organisms changes along the line
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What physical factors could we measure by counting along a transect?
Physical factors such as; light levels, soil pH, water availability that might affect the growth of the plant along the transect.
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What can a change in the distribution of organisms indicate?
A change in the environment, due to either natural causes or intervention from humans (litter or CO2 released from cars)
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What makes an investigation reproducible? What makes an investigation valid?
When the investigation can be done by another person and that person can obtain the same results. An investigation can be made valid if it answers the question.
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When is it best to use a quadrate random sampling? When is it best to use measuring along a transect?
If you want to measure the distribution of plant (quadrates), if you want to measure the change in distribution over a range of habitats.
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Why is it important to have a larger sample size? What does a change in the distribution of organisms suggest?
To make your data more reproducible and valid.A change in distribution of species are often used as evidence for environmental change.
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Why is it better to have more control variables?
So that other scientists can carry out the same investigation under the same conditions, increasing the reproducibility of the results.
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Card 2

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What do plants and algae photosynthesise for?

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For respiration, growth and reproduction

Card 3

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What is the word equation for photosynthesis?

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Card 4

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Where are chloroplasts found?

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Card 5

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Explain what happens during photosynthesis? -mention chlorophyll/glucose/oxygen

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