Topic 1- Key concepts

Question 1

Describe the tests for sugars

Answer 1

Add benedict’s reagent (which is blue) to a sample and heat in a water bath that is set to 75 degrees, if the test is positive it will form a colour precipitate

Question 2

What is the positive result for a reducing sugar

Answer 2

Brick red

Question 3

How to test for starch

Answer 3

Add iodine solution

Question 4

What is the test for lipids

Answer 4

Shake the test substance with ethanol, pour the solution into water.

Question 5

Positive test for lipids

Answer 5

Milky emulsion

Question 6

Protein test

Answer 6

Add a few drops of potassium hydroxide (to make the solution alkaline.)
Then add copper (II) sulfate solution

Question 7

Positive test for proteins

Answer 7

Purple

Question 8

Negative test for proteins

Answer 8

Blue

Question 9

Describe the experiment to investigate the effect of pH on enzyme activity

Answer 9

Set up a Bunsen burner, heatproof mat, tripod and gauze.

Place a beaker of water on the gauze and adjust the flame to keep the water at about 35°C.

Now put two drops of iodine solution into each spot of a spotting tile.

Add 2 cm3 of amylase enzyme solution to a test tube.

Place 2 cm3 of starch solution into the same tube.

Finally add 1 cm3 of pH solution to the tube. This will keep the pH constant.

Mix the solution in the test tube and place it into the beaker of water on the Bunsen burner.

Use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile.

Repeat until the iodine solution stops turning black.

Record the time this takes.

Repeat with different pH solutions.

Question 10

What three things affect rate of reaction

Answer 10

Temperature, pH, Substrate concentration

Question 11

Give an example of how Ciliated epithelial cells are useful in the body

Answer 11

The lining of the airways contains lots of ciliated epithelial cell. These help to move muccs up to the throat so it can be swallowed and not reach the lungs

Question 12

Function of cytoplasm

Answer 12

Gel-like substance where chemical reactions take place, contains enzymes

Question 13

Function of cell membrane

Answer 13

Holds the cell together and controls what goes in or out

Question 14

Name three things that plant cells have that animals dont

Answer 14

Cell wall
Large vacuole
Chloroplasts

Question 15

Function of cell wall

Answer 15

Supports the cell and strengthens it- made of cellulose

Question 16

Function of vacuole

Answer 16

Contains cell sap, maintains internal pressure to support the cell

Question 17

Function of chromosomal DNA

Answer 17

Contol’s the cells activities and replication- floats free in the cytoplasm

Question 18

Function of plasmid DNA

Answer 18

Small loops of extra DNA that aren’t part of the chromosome- contains genes for drug resistane