Chapter 8 - Summary Questions Flashcards
Write the word equation for photosynthesis.
Carbon dioxide + water —–> (light) glucose + oxygen
Name the green pigment in plants and algae.
Chlorophyll.
Name three factors that affect the rate photosynthesis.
Light intensity, temperature, carbon dioxide concentration.
Name the insoluble storage carbohydrate found in potato tubers.
Starch.
Describe a simple method to investigate photosynthesis for a given factor.
Use a water plant placed in water and count the bubbles of oxygen produced or collect the oxygen in an inverted test tube.
Describe three adaptations of a leaf for photosynthesis.
Three from: a leaf is thin, broad and flat; has air spaces inside; has stomata (with guard cells); has veins / xylem and phloem; has mesophyll cells containing a lot of chloroplasts.
Why do plants require nitrate ions?
To convert glucose into amino acids / protein for growth.
a) What is meant by a limiting factor?
b) Give one example of a factor that limits photosynthesis.
a) a factor that stops photosynthesis increasing above a certain level.
b) one from: light intensity, colour of light, carbon dioxide concentration, temperature.
In an investigation to find the effect of light intensity on the rate of photosynthesis, a student set up the following apparatus: he placed a water plant in a boiling tube, filled the tube with water containing dissolved sodium hydrogencarbonate, and supported the tube in a rack. Then he placed a lamp 40cm from the plant and counted the oxygen bubbles it gave off in 1 minute. He moved the lamp towards the plant 10cm at a time and counted the bubbles for each position of the lamp.
a) What is the independent variable in this investigation?
b) What is the dependant variable?
c) What other factor will change as the lamp moves nearer the plant in the boiling tube?
d) How could the student reduce the effect of the factor named in c?
e) Which factor will become limiting?
f) How could the student reduce the effect of the limiting factor?
g) What other measurement did the student make, apart from number of bubbles, to calculate the rate of photosynthesis?
a) light intensity
b) number of oxygen bubbles
c) temperature
d) stand the boiling tube in a beaker of water
e) carbon dioxide concentration
f) provide fresh water and sodium hydrogencarbonate for each position of the lamp
g) time
Using the inverse law, what is the change in light intensity when a lamp is moved from 40cm to 20cm from a plant?
An increase in intensity of 1/4 or 0.25
Explain how tomato growers can reduce the effects of limiting factors in order to obtain larger crops.
Grow the tomatoes in greenhouses or polytunnels and increase the temperature with heaters; use lamps to extend the hours of light; control the levels of carbon dioxide; use hydroponics to supply nitrate and other essential ions.
What factors do tomato growers need to take into account to maximise their profits.
Costs of electricity of providing carbon dioxide of hydroponic solutions of computer technology to control the conditions, of greenhouse / polytunnels and other equipment, labour.
