bio paper 3

Question 1

How does osmosis work? Give me an example

Answer 1

The diffusion of WATER particles across a semi-permeable membrane from an area of HIGH WATER POTENTIAL (so lower solute) to an area of LOW WATER POTENTIAL (higher solute). An example is the osmosis of water into root hair cells.

Question 2

How does active transport work? Give me an example

Answer 2

The movement of cells from an area of LOW CONC. to HIGH CONC. AGAINST the concentration gradient, through carrier proteins using ATP that comes from respiration. An example is the active transport of mineral ions into root hair cells.

Question 3

What are the steps of the cell cycle?

Answer 3

• cell growth of daughter cells
• DNA replication (dna unzips and forms pairs with nucleotides, making 2 identical molecules)
• cell growth - with the replicated DNA inside
• movement of chromosomes (line up in the middle, the copies separate, and move to opposite ends of the cell, forming two nuclei)
• cytokinesis (cell splits into two separate daughter cells)

Question 4

What is the colour change in phenolpththalein?

Answer 4

Turns from pink to colourless in an alkali solution

Question 5

What side of the plant does auxin move to when there is an effect on gravity?

Answer 5

The BOTTOM of the shoots

Question 6

Why is hypothermia harmful to the body?

Answer 6

• enzymes react less and slower, slowing/stopping metabolism
• blood flow is also reduced

Question 7

Test for protein?

Answer 7

Biuret’s solution from blue to purple

Question 8

Test for sugars?

Answer 8

Benedict’s solution colour change to red

Question 9

Test for starch?

Answer 9

Iodine solution from yellow-black to blue-black

Question 10

Test for lipids?

Answer 10

Add ethanol, and pour the liquid solution into a test tube of water. Cloudy liquid or emulsion indicates the presence of lipids

Question 11

How do guard cells help control the size of the stoma?

Answer 11

Water moves into guard cells through osmosis from surrounding cells, because the water potential in the guard cells is reduced. As a result, the guard cells are filled with water, becoming turgid. They have unevenly thick walls, so as they open, the cells curve and open to control the size of the stoma.

Question 12

Which blood vessels IN THE HEART have valves?

Answer 12

Aorta and pulmonary after (in the body though, it’s veins)

Question 13

When would half of the enzymes hypothetically be occupied with substrate?

Answer 13

When the rate of reaction is at its half-way point

Question 14

Why would leaves rise in a closed space during photosynthesis?

Answer 14

Because oxygen is produced