cotrasport

Question 1

cotransport method

Answer 1

1. Na+ ions leave epithelial cell and enter blood;

Penalise for Na without ions once.

2. (Transport out is by) active transport / pump / via carrier protein using ATP;

Reject channel protein

3. So, Na+ conc. in cell is lower than in lumen (of gut);

Maintains diffusion gradient for Na+ from lumen/into cells;

4. Sodium/Na+ ions enter by facilitated diffusion;

Accept diffusion/from high to low concentration through a symport/cotransport protein

5. Glucose absorbed with Na+ ions against their concentration/diffusion gradient / glucose absorbed down an electrochemical gradient;

Question 2

contrasport a01

Answer 2

1- This is the movement of substances across the cell membrane via carrier protein.

2- Cotransporter protein can be found at the cell surface membrane of the epithelium cells lining the ileum.

3- Sodium ions move into the cell from the ileum by facilitated diffusion, carrying amino acid molecules along with them via the cotransporter protein.

4- Sodium is then transported out by active transport and the sodium potassium pump via the carrier protein using ATP into the blood.

5- This lowers the sodium ion concentration inside the cell and creates a sodium ion concentration gradient between the ileum and the epithelial cell.

6- The amino acid concentration inside the epithelial cell increases and amino acids enter the blood via facilitated diffusion

Question 3

A02 respiration link - glucose

Answer 3

• aerobic respiration, glycolysis, to occur.

1- Glucose is phosphorylated in to glucose phosphate in the cytoplasm by the hydrolysis of two ATP molecules to ADP and Pi.

2- This provides energy to allow glucose to be split to triose phosphate.

3- This is then oxidised (hydrogen is removed), reducing NAD to NADH.

4- Finally, triose phosphate is converted into pyruvate, which regenerates two molecules of ATP from ADP per molecule of pyruvate.

Question 4

A02 link - AA - antibodies

Answer 4

1- proteins - with variable regions

2- that bind specifically to antigens on pathogens.

3- this specific binding neutralizes pathogens and marks them for destruction by immune cells, such as phagocytes.

4- The importance of antibodies lies in their role in adaptive immunity, providing targeted defence against infections and contributing to long-term immunity through memory cells.

Question 5

What is cotransport?

Answer 5

Cotransport is the movement of substances across the cell membrane via carrier protein.

Question 6

Where can cotransporter proteins be found?

Answer 6

Cotransporter proteins can be found at the cell surface membrane of the epithelial cells lining the ileum.

Question 7

How do sodium ions move into the cell from the ileum?

Answer 7

Sodium ions move into the cell from the ileum by facilitated diffusion, carrying amino acid molecules along with them via the cotransporter protein.

Question 8

How is sodium transported out of the cell?

Answer 8

Sodium is transported out by active transport and the sodium-potassium pump via the carrier protein using ATP into the blood.

Question 9

What effect does sodium transport have on sodium ion concentration inside the cell?

Answer 9

This lowers the sodium ion concentration inside the cell and creates a sodium ion concentration gradient between the ileum and the epithelial cell.

Question 10

What happens to amino acid concentration inside the epithelial cell?

Answer 10

The amino acid concentration inside the epithelial cell increases and amino acids enter the blood via facilitated diffusion.