Assorted

Question 1

What is the formula for glucose?

Answer 1

c6h12o6

Question 2

What is maltose made up of?

Answer 2

Glucose + glucose

Question 3

What are the structural differences between glucose and ribose? (2)

Answer 3

• glucose is c6h12o6, ribose is c5h10o5

- ribose is pentose sugar, glucose is hexose sugar

Question 4

How do the properties of water lead to surface tension? (3)

Answer 4

• water molecules are polar
• therefore form hydrogen bonds
• therefore are cohesive

Question 5

What are the least dense cell components?

Answer 5

glucose, enzymes, ATP, amino acids, proteins

Question 6

If you separate out ER through centrifugation then how can you next separate SER and RER? (2)

Answer 6

Use smaller intervals of density,

RER is more dense

Question 7

Explain why cells carry out mitosis (2)

Answer 7

Growth/repair,

because this needs genetically identical cells

Question 8

Explain what happens to the DNA content and number of chromosomes by the end of interphase? (4)

Answer 8

• DNA replication
• therefore DNA content doubles
• new chromatids are formed
• but number of chromosomes stays the same

Question 9

Why are two results seen in plants for anaphase in root tip not identical? (3)

Answer 9

• student may have picked different part of root tip
• it is difficult to identify stage of mitosis
• different plants have different rates of growth

Question 10

Explain how pollen tubes could still grow in the presence of an inhibitor (2)

Answer 10

Because some mRNA could still be made, so some protein synthesis can take place.

Question 11

Describe process of translation (5)

Answer 11

• mRNA is attached to ribosome
• tRNA is attached to a specific amino acid
• tRNA anticodon binds with mRNA codon
• peptide bonds form between amino acids
• process involves stop/start codons

Question 12

In which stage does independent assortment take place?

Answer 12

metaphase I

Question 13

In which stage does crossing over take place?

Answer 13

prophase I

Question 14

Describe process of crossing over (4)

Answer 14

• Homologous chromosomes line up
• chromatids overlap
• break in DNA occurs
• genetic information exchanged between chromatids

Question 15

What are chiasmata?

Answer 15

overlaps in chromatids

Question 16

How can you use antibiotics to identify whether a bacterium is gram positive or negative? explain (3)

Answer 16

If antibiotics worked then gram positive because gram positive have a cell wall with more peptidoglycan, therefore is a target site for antibiotic.

Question 17

How are proteins made in cells? (5)

Answer 17

• DNA unzips because hydrogen bonds are broken
• mRNA made by complementary base pairing
• mRNA leaves nucleus and attaches to ribosomes
• tRNA anticodon attaches to mRNA codon
• amino acids form peptide bonds in translation

Question 18

Why might a point mutation mean an enzyme can’t work anymore? (3)

Answer 18

Mutation would affect active site,
change in sequence of amino acids,
glucose would not bind so no enzyme substrate complex.

Question 19

Describe how a quaternary structure is formed after protein synthesis? (2)

Answer 19

Polypeptides fold up into a helix or beta pleated sheet arrangement,
two or more polypeptides join together by H bonds/disulphide bridges.

Question 20

How would a DNA molecule with 4 nucleotides be arranged?

Answer 20

Two in a line, two upside down antiparallel

Question 21

Why do some bases not code for amino acids? (2)

Answer 21

Some are start/stop codons, some are introns (non-protein coding)

Question 22

How do you work out activation energy?

Answer 22

Max potential energy - initial potential energy

Question 23

Why is reaction rate faster for amylopectin than amylose when both put in with amylase? (2)

Answer 23

• active site is more complementary to amylopectin

- amylopectin has more terminal glycosidic bonds/more side branches

Question 24

What are liposomes?

Answer 24

Spherical sac surrounded by phospholipid molecules, containing medicine or treatment.

Question 25

Some drugs prevent proper formation of spindle fibres. How can this help treat cancer? (3)

Answer 25

• fibres can’t contract
• contraction of fibres needed to cause chromatids to separate
• so chromatids cannot be pulled to opposite poles so new cells can’t be made

Question 26

How does the nitrogen experiment support DNA replication theory? (4)

Answer 26

DNA is replicated semi-conservatively
- heavy DNA disappears after first cycle
- after one replication DNA is intermediate as one strand comes from original DNA and one from a newly constructed strand
- as you get more DNA being formed, the increase is all
due to newly formed strands, which are all light DNA

Question 27

How could you use a time vs mean absorbance of colorimeter to find initial RoR?

Answer 27

Draw a tangent to the curve of the graph.
Tangent drawn following only the first few seconds of the curve.
Read off single values for absorbance and time.
Calculate gradient of the line to find the rate.

Question 28

Why do fruits only go brown after being cut?

Answer 28

Substrate and enzyme contained within cells so cannot mix, and don’t have oxygen supply
so when they get cut they can mix and get oxygen.

Question 29

Why does lemon juice prevent browning? (1)

Answer 29

change in pH!!!!