January WJEC 2010 Unit 1

Question 1

Describe differences between DNA and RNA?

Answer 1

DNA
contains pentose sugar
found in the nucleus
thymine is not present
consists of double helix
molecules are not short lived
not associated with ribosomes

RNA
contains pentose sigar
found in nucleus
Thymine is never present
doesn’t have double helix
molecules are short lived
associated with ribosomes

Question 2

Function of Nuclelous?

Answer 2

Ribosome
Synthesis of rRNA

Question 3

Function of inner membrane folded into cristae?

Answer 3

increases surface area for ATP synthesis

Question 4

What is the function of lysosome?

Answer 4

cell lysis

Question 5

Structural feature of golgi body?

Answer 5

stack of cisternae flattened sacs

Question 6

One method that could be used to immobilise the urease?

Answer 6

alginate beads

Question 7

3 advantages of immobilised enzymes ?

Answer 7

Product is easily recovered
so cheaper to use
greater stability despite variations in temp
enzymes easily removed

Question 8

Function of partially permeable membrane in this biosensor?

Answer 8

allows urea through
prevents passage of blood cells

Question 9

Describe the role of this transducer?

Answer 9

converts chemical signal into an electrical signal to record levels of urea

Question 10

Explain why thetemps of 2 samples would be the same?

Answer 10

increased temp increases enzymes activity
more ammonium ions formed

Question 11

Medical condition whch a biosensor can detect?

Answer 11

diabetes

Question 12

4 events during interphase?

Answer 12

replication of DNA
increase in cell size
chromosomes exist as chromatids
replication of organelles
ATP synthesis
Protein synthesis

Question 13

What stage of mitosis where chromatids line up at the equator?

Answer 13

metaphase

Question 14

Where centromeres split?

Answer 14

anaphase

Question 15

Where spindle fibres contract + shorten?

Answer 15

anaphase

Question 16

Where chromsomes are first visible as pair of chromatids?

Answer 16

prophase

Question 17

Where nuclear membrane reforms?

Answer 17

telophase

Question 18

Explain answer in terms of water potential?

Answer 18

water moves from a region of high water potential to a region of lower water potential by osmosis

Question 19

Explain how this condition could have arisen?

Answer 19

Plasmolysis
cell in concentrated solution / low water potential;
water passes out;
cytoplasm/vacuole shrinks

Question 20

Explain how pressure is built up in cell X?

Answer 20

water passes into cell by osmosis;
cytoplasm expands
cell becomes turgid;
as cytoplasm push against wall;
wall inelastic / resists further expansion.

Question 21

Reaction involved in breaking the bond?

Answer 21

Hydrolysis

Question 22

What is explained by the phrase arranged in the same way as he chains in cellulose?

Answer 22

Hydroxyl groups point outwards;
link with neighbouring chains;
via hydrogen bonding;
to form microfibrils;
strong structure because of large number of hydrogen bonds;
chains associate in groups
Bet glucose units

Question 23

Highest lvel of protein structure in lysosome?

Answer 23

Tertiary

Question 24

Importance of S-S linkages to functioning of enzyme?

Answer 24

links between different parts of polypeptide chains;
produces a specific shape for the lysozyme;
active site is complementary to substrate;
allows enzyme – substrate complexes to form;

Question 25

2 variables controlled during investigation?

Answer 25

equal volumes of hydrogen peroxide
concentration of hydrogen peroxide
pH
temp
same time intervals between measuremenrs

Question 26

Why does liver contain most catalse ?

Answer 26

liver- most metabolically active
produces most hydrogen peroxide
needs tobe broken down due to toxicity