A Level Biology
- ANSWER✅✅✅Contrast the processes of facilitated diffusion and active transport.
- ANSWER✅✅✅MM is caused by a faulty receptor protein in cell surface membranes
- A phagocyte recognises the foreign antigens on a pathogen.
- The cytoplasm of the phagocyte engulfs the pathogen
- The pathogen is now contained in a phagocytic vacuole
- A lysosome fuses with the phagocyte vacuole. The lysozymes break down the pathogen
- The phagocyte presents the pathogens antigens on its surface to activate other immune system cells. -
ANSWER✅✅✅Explain the process of phagocytosis
- A T-cell is another type of white blood cell. It has receptor proteins on its surface that bind to
complimentary antigens presented by the phagocytes. This activates the T-cell.
- Different T-cells react in different ways. Helper T-cells release chemical signals that activate and
stimulate phagocytes and cytotoxic T-cells which kill abnormal and foreign cells. They also activate B-
cells. - ANSWER✅✅✅Explain how the phagocytes activate the T-cells
- Active transport uses ATP because it goes against a concentration gradient.
- Facilitated diffusion uses carrier and channel proteins while going down a concentration gradient. -
ANSWER✅✅✅Contrast the processes of facilitated diffusion and active transport.
- Active transport uses ATP to go against a concentration gradient
- Facilitated diffusion uses carrier and channel proteins
- And goes down a concentration gradient. - ANSWER✅✅✅Contrast the processes of facilitated
diffusion and active transport.
- Against a concentration gradient
- Requires ATP - ANSWER✅✅✅DETECT:
Active Transport
A Level Biology
, A Level Biology
- Antigen (on HIV) changes;
- Specific antibody / receptor no longer binds to new antigen; - ANSWER✅✅✅HIV shows a lot of
antigenic variability. Why might a vaccine not be effective against HIV?
- As it gives you a 3D image. - ANSWER✅✅✅Give one advantage of using SEM rather than TEM.
- B-cells are also a types of white blood cell that are covered in antibodies. Each B-cell has a different
shaped antibody on its membrane, so only a complimentary antigen will produce an antigen-antibody
complex.
- When the antibody meets with a complimentary antigen, it binds to it. This, together with the
substances from helper T-cells activates the B-cell. This is called clonal selection. The activated B-cell
divides into plasma cells - ANSWER✅✅✅Explain the role of B-cells in the immune response
- Because it gives you a 3D image - ANSWER✅✅✅Give one advantage of using SEM rather than TEM
- Beta glucose has alternate 1-4 bonds meaning that it is straight and not bent.
- Long unbranched chains
- Joined by hydrogen bonds
- Forms microfibrils (Very strong) - ANSWER✅✅✅The structure of cellulose is related to its role in
plant cell walls. Explain how.
- Cell makes new viruses
- Makes proteins and RNA in ribosomes
- DNA copy of RNA put in hosts DNA - ANSWER✅✅✅Describe how new viruses are produced after
HIV has infected a T cell.
- Children receive (HIV) antibodies from their mothers / maternal antibodies
- Solution will always turn blue / will always test positive - ANSWER✅✅✅A mother who was
infected with HIV gave birth to a baby. The baby tested positive using this test. This does not prove the
baby is infected with HIV.
Explain why.
A Level Biology
- ANSWER✅✅✅Contrast the processes of facilitated diffusion and active transport.
- ANSWER✅✅✅MM is caused by a faulty receptor protein in cell surface membranes
- A phagocyte recognises the foreign antigens on a pathogen.
- The cytoplasm of the phagocyte engulfs the pathogen
- The pathogen is now contained in a phagocytic vacuole
- A lysosome fuses with the phagocyte vacuole. The lysozymes break down the pathogen
- The phagocyte presents the pathogens antigens on its surface to activate other immune system cells. -
ANSWER✅✅✅Explain the process of phagocytosis
- A T-cell is another type of white blood cell. It has receptor proteins on its surface that bind to
complimentary antigens presented by the phagocytes. This activates the T-cell.
- Different T-cells react in different ways. Helper T-cells release chemical signals that activate and
stimulate phagocytes and cytotoxic T-cells which kill abnormal and foreign cells. They also activate B-
cells. - ANSWER✅✅✅Explain how the phagocytes activate the T-cells
- Active transport uses ATP because it goes against a concentration gradient.
- Facilitated diffusion uses carrier and channel proteins while going down a concentration gradient. -
ANSWER✅✅✅Contrast the processes of facilitated diffusion and active transport.
- Active transport uses ATP to go against a concentration gradient
- Facilitated diffusion uses carrier and channel proteins
- And goes down a concentration gradient. - ANSWER✅✅✅Contrast the processes of facilitated
diffusion and active transport.
- Against a concentration gradient
- Requires ATP - ANSWER✅✅✅DETECT:
Active Transport
A Level Biology
, A Level Biology
- Antigen (on HIV) changes;
- Specific antibody / receptor no longer binds to new antigen; - ANSWER✅✅✅HIV shows a lot of
antigenic variability. Why might a vaccine not be effective against HIV?
- As it gives you a 3D image. - ANSWER✅✅✅Give one advantage of using SEM rather than TEM.
- B-cells are also a types of white blood cell that are covered in antibodies. Each B-cell has a different
shaped antibody on its membrane, so only a complimentary antigen will produce an antigen-antibody
complex.
- When the antibody meets with a complimentary antigen, it binds to it. This, together with the
substances from helper T-cells activates the B-cell. This is called clonal selection. The activated B-cell
divides into plasma cells - ANSWER✅✅✅Explain the role of B-cells in the immune response
- Because it gives you a 3D image - ANSWER✅✅✅Give one advantage of using SEM rather than TEM
- Beta glucose has alternate 1-4 bonds meaning that it is straight and not bent.
- Long unbranched chains
- Joined by hydrogen bonds
- Forms microfibrils (Very strong) - ANSWER✅✅✅The structure of cellulose is related to its role in
plant cell walls. Explain how.
- Cell makes new viruses
- Makes proteins and RNA in ribosomes
- DNA copy of RNA put in hosts DNA - ANSWER✅✅✅Describe how new viruses are produced after
HIV has infected a T cell.
- Children receive (HIV) antibodies from their mothers / maternal antibodies
- Solution will always turn blue / will always test positive - ANSWER✅✅✅A mother who was
infected with HIV gave birth to a baby. The baby tested positive using this test. This does not prove the
baby is infected with HIV.
Explain why.
A Level Biology
