Organisms in the Environment Flashcards
Which organisms can carry out photosynthesis?
Only green plants and algae
What is the word equation of photosynthesis?
carbon dioxide + water (+ light energy) → glucose + oxygen
What is the process of photosynthesis?
- CO2 is taken in by leaves and water is taken up by roots
- Cholorophyll traps the light energy needed for photosynthesis
- This energy is used to convert the CO2 + water into glucose
What role do choloroplasts play in photosynthesis?
They contain cholorphyll which absorbs the Sun’s light energy
What is released as a by-product of photosynthesis?
Oxygen
What is some of the glucose produced by photosynthesis converted into?
Insoluble starch so it can be stored
How can show that photosynthesis has occured in a leaf?
- Iodine can be used to test for starch.
- Variegated leaves have patches of green (with cholorphyll) and white (without cholorphyll)
- Only green patches will turn the iodine solution blue-black to show the presence of starch
- Starch shows that photosynthesis has taken place because it is made of some of the glucose created that has been stored by the plant
What does variegated mean?
Having different colours
What is a limiting factor?
Something that limits the rate of photosynthesis
If you want to find out the effect of a certain limiting factor what must you also be aware of?
Other limiting factors that can effect the plant
You should make sure to control these factors in your experiment
What is the independant variable?
The one being tested
What is the dependant variable?
The one that you measure
It is the one that changes due to the independant variable changing (although not always…
Give some examples of limiting factors for photosynthesis and why they limit it
- Light - slows down process as it provides the energy for it. May be limited to plants that are in the shade
- Cold - enzymes do not work effectively
- Too little CO2 - needed for process to take place. Mya be due to plant being in an enclosed space
Draw three graphs showing the effect of CO2 concentration, light intensity, and temperature on the rate of photosynthesis
What are the uses of soluble glucose?
- Can be converted into insoluble starch to be stored
- Used for respiration
- Converted into fats + oils to be stored
- Used to produce cellulose which strengthens cell walls
- Used to produce proteins
Why do plant and algal cells also need a supply of mineral ions and nitrate ions?
In order to make proteins
How do plants absorb nitrate ions?
From the soil (with their roots)
How do algae absorb nitrate ions?
From the water they live in
How do plant growers try to give their plants the best conditions for growth?
By controlling the environment and limiting factors of photosynthesis
How can greenhouses and polytunnels be used by plant growers and what are the advantages + disadvantages of them?
- If the greenhouse has lamps or heaters the rate of growth may increase. However, this may stop is the light intensity/temperature is too high
- Carbon dioxide can be added to the air to increase the growth rate.
- Nitrate ions can be added to the soil to ensure plants can make the proteins they need for healthy growth
How might a plant grower evaluate the effectiveness of using greenhouses or polytunnels?
By comparing the biomass of plants grown indoors and outdoors
What physical factors may affect the distribution of organisms?
- Temperature - Arctic plants are small, limiting the number of plant eaters that can survive in that area
- Availability of nutrients - Most plants struggle to grow where there are few mineral ions. This also limits the number of animals
- Amount of light - Few plants live on the forest floor because light is blocked out by trees. Shaded plants have broader leaves or more cholorphyll
- Availability of water
- Availability of oxygen
- Availability of CO2
How can quantitative data be obtained?
- Random quantitive sampling using a quadrat
- Sampling along a transect
What is quantitive sampling?
Sampling which records the numbers of organisms not just the types
What is a quadrat?
An aparatus used for sampling
It is a square frame made of metal or wood which may be subdivided into a grid
How can quadrats be used?
They can be placed randomly or along a transect
The number of organisms in the quadrats can then be counted and used to estimate the number of orgamisms in that particular area
(e.g. daisies in a field)
Why is sample size important?
In a large field, enough random quadrats must be placed in otder to be sure the sample is representative of the whole field
What is a transect?
A measured line along which ecological measurements are made
It is not random
Aside from the number of organisms, what can also be measured at each point along a transect?
The physical factors
Why is using a transect a good way of colelcting data and why might using one be better than random sampling?
Supplies a lot of information about the habitat and the organsisms in it
(e.g. can also be used to measure physical factors and compare how distribution changes along the transect)
Why can investigations about the distribution of organisms in their environment be difficult?
They are often done over a long period of time
Not all variables can be controlled
Complete the sentence:
In a valid investigation, all…
…possible variables must be controlled
What does valid mean?
Suitablity of an investigative proceedure to test a hypothesis
What does repeatable mean?
The origional experimenter repeats the experiment using the same method + equipment and gets the same results
What does reproducable mean?
The experiment can be carried out by a different person or with different equipment and the same results can be produced
Why is sample size an important factor in obtaining valib, repeatable, and reproducable data?
If it is too small it may not be representative
What makes data/an investigation valib/reliable?
- Validity - controlling all possible variables
- Repeatability - the same person repeats it with the same equipment and gets the same results
- Reproducability - different people repeat the experiment or different equipment is used the the same results are obtained
