Get premium membership and access questions with answers, video lessons as well as revision papers.
i) Thickness of membranes and tissues: The thicker the membrane or tissue, the lower the rate of diffusion. This is because the distance to be covered by diffusing molecules is greater. However if the membrane is thin, the rate of diffusion is high.
ii) Size of molecules: small and light molecules diffuse faster than large and heavy molecules.
iii) Temperature: An increase in temperature increases the energy content of molecules and causes them to move faster. An increase in temperature therefore increases the rate of diffusion while a decrease in temperature decreases rate of diffusion.
iv) Surface area of the of the volume ratio
v) Concentration gradient/ diffusion gradient
johnmulu answered the question on April 29, 2017 at 06:00
- In an investigation, a student extracted three pars of pawpaw cylinders using a cork borer. The cylinders were cut back to 50mm lenth and placed in a beaker containing a solution. The results after 40 minutes were as shown in the table below.(Solved)
In an investigation, a student extracted three pars of pawpaw cylinders using a cork borer. The cylinders were cut back to 50mm lenth and placed in a beaker containing a solution. The results after 40 minutes were as shown in the table below.
a) Account for the results in the table above
b) What would be suitable control set-up for the investigation?
Date posted: April 29, 2017. Answers (1)
- The diagram s below shows an experiment set-up to investigate a certain process in a plant tissue.(Solved)
The diagram s below shows an experiment set-up to investigate a certain process in a plant tissue.
Explain the results obtained after 30 minutes
Date posted: April 29, 2017. Answers (1)
- Distinguish between haemolysis and plasmolysis.(Solved)
Distinguish between haemolysis and plasmolysis.
Date posted: April 29, 2017. Answers (1)
- Name the type of movement that occurs within a plant cell.(Solved)
Name the type of movement that occurs within a plant cell.
Date posted: April 29, 2017. Answers (1)
- a) Distinguish between diffusion and active transport
b) State one role that is played by osmosis in
i) Plants
ii) Animals(Solved)
a) Distinguish between diffusion and active transport
b) State one role that is played by osmosis in
i) Plants
ii) Animals
Date posted: April 29, 2017. Answers (1)
- The diagram below show a red blood cell that was subjected to a certain treatment (Solved)
The diagram below show a red blood cell that was subjected to a certain treatment
Account for shape of the cell at the end of the experiment
Date posted: April 28, 2017. Answers (1)
- Distinguish between diffusion and osmosis(Solved)
Distinguish between diffusion and osmosis.
Date posted: April 28, 2017. Answers (1)
- An experiment was set up as shown below(Solved)
An experiment was set up as shown below
The set up was left for 30 minutes.
a) State the expected results.
b) Explain your answer in (a) above
Date posted: April 28, 2017. Answers (1)
- State the importance of osmosis in plant(Solved)
State the importance of osmosis in plant
Date posted: April 28, 2017. Answers (1)
- a) What is diffusion?
b) How do the following factors affect the rate of diffusion? (Solved)
a) What is diffusion?
b) How do the following factors affect the rate of diffusion?
i) Diffusion gradient
ii) Surface area to volume ratio
iii) Temperature
Date posted: April 28, 2017. Answers (1)
- Why is oxygen important in the process of active transport in cells? (Solved)
Why is oxygen important in the process of active transport in cells?
Date posted: April 28, 2017. Answers (2)
- Explain what would happen to a red blood cells if they are placed in a concentrated salt solution(Solved)
Explain what would happen to a red blood cells if they are placed in a concentrated salt solution
Date posted: April 28, 2017. Answers (1)
- State the functions of the following parts of a light microscope.
a) Objective lens
b) Diaphragm
(Solved)
State the functions of the following parts of a light microscope.
a) Objective lens
b) Diaphragm
Date posted: April 28, 2017. Answers (1)
- a) State two advantages of using a coverslip when preparing a specimen for observation under a light microscope.
b) How is the low power objective lens manipulated to focus a specimen for observation under a light microscope?
(Solved)
a) State two advantages of using a coverslip when preparing a specimen for observation under a light microscope.
b) How is the low power objective lens manipulated to focus a specimen for observation under a light microscope?
Date posted: April 28, 2017. Answers (1)
- State one function of each of the following cell organelles:
(Solved)
State one function of each of the following cell organelles:
a) Golgi bodies
b) Lysosomes.
Date posted: April 28, 2017. Answers (1)
- A student drew a 6 cm long diagram of a plant flower. If the actual length of the flower was 12 cm, calculate the magnification of the drawing made by the student. Show your working(Solved)
A student drew a 6 cm long diagram of a plant flower. If the actual length of the flower was 12 cm, calculate the magnification of the drawing made by the student. Show your working
Date posted: April 28, 2017. Answers (1)
- State one way in which each of the following is structurally adapted to its function:
a) neurone;
b) Mitochndrion.
(Solved)
State one way in which each of the following is structurally adapted to its function:
a) neurone;
b) Mitochndrion.
Date posted: April 28, 2017. Answers (1)
- Name the organelle that is involved in each of the following(Solved)
Name the organelle that is involved in each of the following
a) Manufacture of lipids
b) Formation of lysosomes
Date posted: April 28, 2017. Answers (1)
- a) Name the part of a light microscope used to bring an image of a specimen into sharp focus.
b) Why is it recommended to keep the stage of the microscope dry?
(Solved)
a) Name the part of a light microscope used to bring an image of a specimen into sharp focus.
b) Why is it recommended to keep the stage of the microscope dry?
Date posted: April 28, 2017. Answers (1)
- The figure below is a fine structure of a generalized animal cell as seen under an electron microscope.(Solved)
The figure below is a fine structure of a generalized animal cell as seen under an electron microscope.
a) Name the parts labeled A and B.
b) How the is structure labeled B adapted to its function?
Date posted: April 28, 2017. Answers (1)