AS Level Biology Topic 1 & 2 Qs

Question 1

Suggest why liver cells of the type shown in the diagram contain many mitochondria

Answer 1

Liver cells carry out more aerobic respiration to convert glucose into glycogen.

Question 2

What organelle contains digestive enzymes?

Answer 2

Lysosomes

Question 3

State two reasons why the blood smear has been stained

Answer 3

So it is easier to distinguish between different types of white blood cells.

Question 4

Suggest one detail made visible by scanning electron OR transmission microscope.

Answer 4

Scanning - Surface Detail
Transmission - Mitochondria/Organelles

Question 5

Suggest one stage during the secretion of a protein that requires energy

Answer 5

Transporting the vesicle to the cell surface membrane

Question 6

3 similarities and difference of a triglyceride molecule and a phospholipid

Answer 6

Similarities -
Both have glycerol,
fatty acid,
Esther bonds between glycerol and fatty acid

Differences -
Triglycerides have 3 fatty acids, whereas phospholipids have 2
Phospholipids are polar, whereas Triglycerides are neutral
Phospholipid form glycolipids whereas Triglycerides bond to C atoms

Question 7

Describe how you could use an emulsion test to show that seeds contain lipids.

Answer 7

Grind up 2cm of seed and put in a test tube,
Add 5cm of ethanol and then shake the tube thoroughly,
Then add 5cm of water and shake gently.

A white (milky) emulsion will form if seeds contain lipids.

Question 8

Describe how the structure of a phospholipid is different to that of a triglyceride

Answer 8

Phospholipid has 2 fatty acids and a phosphate group
Triglyceride has 3 fatty acids

Question 9

Explain why the adispose layer is described as tissue

Answer 9

Same type of cells working together with the same function

Question 10

Triglyceride properties and functions

Answer 10

Triglyceride can stay at right state as oily droplets at body temperature underneath the skin

Question 11

Explain why triglycerides are not considered to be polymers

Answer 11

Not made of repeating monomers

Question 12

If 2 alpha glucose are linked together, what would the products be?

Answer 12

Water & Sucrose

Question 13

Large numbers of monomers joining together

Answer 13

Polymerisation

Question 14

Enzyme that could reverse hydrolysis

Answer 14

Maltose and Water

Question 15

2 molecules with the same formula but different structures

Answer 15

Structural isomers

Question 16

Molecular formula of lactose

Answer 16

C12H22O11

Question 17

What is a reducing sugar?

Answer 17

A sugar that donates electrons to another chemical

Question 18

What is a “non reducing” sugar?

Answer 18

A sugar that cannot donate electrons therefore cannot be oxidised

Question 19

Suggest why trehalose might not give a positive test for non-reducing sugars using benedicts reagent?

Answer 19

There are no free reducing groups to reduce Cu2+ to Cu+ due to the 1-1 glycosidic bond.

Question 20

What variables go on the x or y axis?

Answer 20

x-axis = independent variable

y-axis = dependent variable

Question 21

Identify and give functions of 3 structures found in plant cells that are absent in animal cells.

Answer 21

Cell wall is found in plant cells, not animal cells -
Function to provide strength and stops cell from bursting when filled with water.

Chloroplasts -
Carries out photosynthesis by absorbing light

Plasmodesma -
Connect adjacent plant cells establishing living bridges between cells.

Question 22

Suggest how you use benedicts solution to compare amount of reducing sugar in 2 solutions

Answer 22

Compare the colour

Question 23

Explain why pure glucose obtained from starch has a dextrose equivalent of 100

Answer 23

All glycosidic bonds are hydrolysed

Question 24

Name monomer found in cellulose

Answer 24

Beta-glucose

Question 25

Explain how cellulose gives cotton its strength

Answer 25

Long straight chains,
Chains side by side held together by Hydrogen Bonds

Question 26

Explain why acid was not used to break down fructose

Answer 26

Acid will alter pH

Question 27

Explain why the R of a reaction of enzymes if:

a) temperature fell

b) pH chained sustainably

Answer 27

(i) molecules have less kinetic energy so fewer collisions less likely for enzyme-substrate complex to form

(ii)change in ph alters the shape of the active site and denatures enzyme so substrate will no longer fit the active site

Question 28

Name one biologically important polymer, other than those mentioned in the passage, which would be found in straw.

Answer 28

Amylose

Question 29

Explain why cellulose digesting enzymes do not digest lignin

Answer 29

Enzymes have a complimentary shape for its substrate so lignin would not fit active site