june 2008 wjec unit 1

Question 2

Cell wall?

Answer 2

mechanical strength due to high tensile strength of cellulose microfibrils
protection
turgidity
prevent bursting
support or shape

Question 3

Chloroplast?

Answer 3

contain photosynthetic pigments which trap light for photosynthesis
site of photosynthesis
absorption of light

Question 4

Plasmodesmata?

Answer 4

connects via cytoplasm filled canals which pass through cell walls
allows transport for symplastc pathway
cytoplasmic flow or symplastc movement of water

Question 5

Cell vacuole?

Answer 5

ensures that cytoplasm is pushed against cell wall to remain turgor

Question 6

Mitochondria?

Answer 6

provides ATP for activation of amino acids

Question 7

Ribosomes?

Answer 7

translation of mRNA joining amino acids to form peptide bonds

Question 8

Endoplasmic reticulum?

Answer 8

ribosomes attached
vesicles pinched off
to be moved into the golgi body
proteins are secreted into it

Question 9

Golgi body?

Answer 9

packages + modifies proteins into secondary , tertiary+ quaternary
produces vesicles containing newly synthesised

Question 10

Cell surface membrane?

Answer 10

absorption of amino acids + secretion of proteins + exocytosis

Question 11

Nucleus?

Answer 11

contains chromosomes in which DNA encodes protein / mRNA

Question 12

Nucleolus?

Answer 12

produces tRNA and RNA to make ribosomes

Question 13

What is the path?

Answer 13

Ribosome
Endoplasmic Reticulum
Golgi Body

Question 14

What are the carbohydrates in the cell wall?

Answer 14

Cellulose

Question 15

Carbohydrates as a storage compound in the cell?

Answer 15

starch
amylopectin
amylose

Question 16

As a component of ribosomes?

Answer 16

ribose

Question 17

Centriole?

Answer 17

point on the opposite sides of cell

Question 18

Bonding involved in the formation of a triglyceride?

Answer 18

ester

Question 18

Bivalent + chromosomes?

Answer 18

are the same

Question 18

Chromatid?

Answer 18

a half of a chromosome

Question 19

Differences between triglyceride + phospholipid?

Answer 19

phospholipids - 2 fatty acids whereas Triglycerides have 3
Triglycerides have no phosphate head, whereas phospholipids do
Phospholipids have hydrophobic tails + hydrophilic heads, making them a polar molecule

Question 20

Why do animals tend to store energy in the form of fat rather than carbohydrate?

Answer 20

Fats have twice as much energy as a carbohydrate

Question 21

Difference between saturated + unsaturated fat?

Answer 21

saturated - solid at room temp
unsaturated - liquid at room temp

unsaturated - kink or bond in tail whereas saturated are straight
saturated - more H molecules

Question 22

Why was sodium carbonate added to the tubes?

Answer 22

to make content of tubes alkali

Question 23

What colour would you expect in tube A after 6 hours incubation?

Answer 23

lipase hydrolyses lipids into fatty acids
Red
pH

Question 24

Explain your answer?

Answer 24

Fatty acids lower the pH, making the contents acidic

Question 25

Why is there no appreciable change in colour observed in tube B?

Answer 25

boiling the enzyme has denatured the active site and the bonds have been broken
the substrate no longer fits the active site as it is no longer complementary
so an enzyme substrate complex cannot be formed

Question 26

Type of uptake with a straight line?

Answer 26

diffusion
as concentration increases, the rate of uptake also increases
it is a continuous process and therefore is not affected by a respiratory inhibitor
passive process so no ATP is required

Question 27

Straight line then plateaus?

Answer 27

facilitated diffusion
the rate of uptake is directly proportional to concentration
however, there becomes no increase in rate

binding site are full
no ATP required - passive process
not affected by respiratory inhibitors
at higher concentration, the rate of uptake slows down + plateaus due to carrier proteins being a limiting factor

Question 28

Straight line then down?

Answer 28

Active transport
carrier proteins are saturated so the rate slows down
affected by a respiratory inhibitor because active transport - active process + requires ATP

Question 29

Complete the lists of RNA found within the cells

Answer 29

Messenger RNA
small interfering RNA
rRNA
tRNA

Question 30

3 differences between RNA and DNA?

Answer 30

RNA is shorter, DNA is longer
RNA has ribose as a sugar whilst DNA has deoxyribose
DNA contains Adenine, thymine, cytosine + guanine whereas DNA contain Adenine, Uracil, Cytosine + Guanine

Question 31

Similarities between interfering RNA and DNA?

Answer 31

both double stranded