WRONG Qs- Term 1

Question 1

Function of endoplasmic reticulum (1 mark):

Answer 1

Protein synthesis

Question 2

Function of Golgi apparatus (1 marks):

Answer 2

Modifying protein (adds carbs to protein) making a glycoprotein

Question 3

Describe the structure and function of the nucleus (4 marks):

Answer 3

Structure:
- double membrane AND pores
- chromosomes
- nucleolus

Function:
- holds genetic information for polypeptides
- DNA replication occurs
- production of mRNA

Question 4

Explain why the organelles visible in the photograph would not have been visible in an optical light microscope (2 marks):

Answer 4

1) low resolution
2) because wavelength of light is not short enough

Question 5

Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope (4 marks):

Answer 5

1) add a drop of water to glass slide
2) obtain thin section and place on slide
3) Stalin with iodine in potassium iodide
4) lower cover slip using mounted needle

Question 6

Describe how a peptide bound is formed between two amino acids to form a dipeptide (2 marks):

Answer 6

1) a condensation reaction- loses a water molecule
2) formed between an amine and hydroxyl group

Question 7

Describe how the secondary structure of a polypeptide is produced by bonds between amino acids (2 marks):

Answer 7

1) hydrogen bonds
2) between NH and C=O group

Question 8

Explain why two proteins have the same number and type of amino acids but different territory structures (2 marks):

Answer 8

1) different primary structure
2) form disulphide bonds in different places

Question 9

Compare and contrast the structure of starch and cellulose (6 marks):

Answer 9

1) starch is bigger and cellulose is smaller
2) starch contains A- glucose and cellulose contains B-glucose
3) both are glucose polymers
4) both contain glycosidic bonds
5) both contain hydrogen, carbon and oxygen only
6) both contain glucose
7) starch is coiled, cellulose is straight

Question 10

Describe how a triglyceride molecule is formed (3 marks):

Answer 10

1) formed between glycerol and three fatty acids
2) ester bond is formed
3) condensation reaction forming 3 molecules of water r

Question 11

Describe how the structure of glycogen is related to it’s function (6 marks):

Answer 11

1) helical so compact
2) branched- more enzymes- faster hydrolysis
3) polymer of glucose so easily hydrolysed
4) large, insoluble molecules do not affect the water potential of the cell
5) glucose polymer so provides respiratory substrate for enzymes

Question 12

Protein associated with DNA in a chromosome:

Answer 12

His tone

Question 13

Describe the role of DNA polymerase in the semi-conservative replication of DNA (3 marks):

Answer 13

1) joins adjacent DNA nucleotides
2) catalyses condensation reactions
3) catalyses formation of phosphodiester bonds between nucleotides

Question 14

Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of their use when studying cells (6 marks):

Answer 14

1) TEM use electrons and optical use light
2) TEM allows for greater resolution so smaller organelles can be observed
3) TEM views only dead/ dehydrated specimens and optical can view live specimens
4) TEM does not show colour, optical can
5) TEM requires a thinner specimen
6) TEM requires a more complex/ time consuming preparation

Question 15

Describe binary fission in bacteria (3 marks):

Answer 15

1) replication of circular DNA
2) replication of plasmids
3) division of cytoplasm to produce daughter cells

Question 16

Describe the role of spindle fibres during mitosis (2 marks):

Answer 16

1) attachment of centromeres
2) separation of centromeres

Question 17

Describe the difference between pre-mRNA and mRNA molecules (2 marks):

Answer 17

1) mRNA has fewer nucleotides, pre-mRNA has more nucleotides
2) mRNA has no introns, only exons, pre-mRNA has both because of splicing

Question 18

Describe how you would use cell fractionation techniques to obtain a sample of chloroplasts from leaf tissue (do NOT include in your answer information about any solutions) (3 marks):

Answer 18

1) macerate/ homogenise
2) centrifuge
3) at increasing speeds until chloroplast fraction obtained

Question 19

Describe three properties of this solution and explain how each property prevented damage to the organelles (3 marks):

Answer 19

1) ice cold, prevents enzyme activity
2) buffered, prevents enzymes from denaturing
3) same water potential, prevents bursting of organelles

Question 20

Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells (5 marks):

Answer 20

1) cell homogenisation to open cells
2) filter to remove large debris
3) use isotonic solution to prevent damage to mitochondria
4) keep cold to reduce damage by enzymes
5) centrifuge at a lower speed to separate nuclei
6) re-spin after nuclei at a higher speed to get mitochondria at bottom of tube

Question 21

Describe the principles and limitations of using a transmission electron microscope to investigate the cell structure (5 marks):

Answer 21

1) electrons enter thin specimen
2) denser parts absorb more electrons
3) so denser parts appear darker
4) cannot look at living material
5) specimen must be very thin

Question 22

Describe the role of one named organelle in digesting bacteria (3 marks):

Answer 22

• lysosomes
• fuse with vesicles
• release hydrolytic enzymes

Question 23

Describe how the process meiosis results in haploid cells (4 marks):

Answer 23

• DNA replication
• two divisions
• separation of homologous chromosomes in first division
• separation of sister chromatids in second division
• produces 4 haploid cells

Question 24

Describe how a sample of chloroplasts could be isolated from leaves (4 marks):

Answer 24

1) break open cell tissue + filter
2) put in a solution which is cold, sam pH, same water potential
3) centrifuge and spin
4) centrifuge at a higher speed so chloroplasts move out

Question 25

Give three structural features found in all virus particles and describe the function of one (2 marks):

Answer 25

• genetic material, capsid, attachment protein
• genetic material codes for viral protein

Question 26

Explain why viruses are described as acellular and non- living (2 marks):

Answer 26

Acellular- no cell-surface membrane
Non living- no metabolic reactions

Question 27

Describe how HIV is replicated (4 marks):

Answer 27

1) attachment proteins attach to receptors on helper T cell
2) nucleic acid enters cell
3) reverse transcriptase converts RNA to DNA
4) viral protein produced
5) virus particles assembled and released from cell

Question 28

Why is the coverslip pressed down in RP2? (2 marks)

Answer 28

• create a thin layer of cells
• so light can pass through

Question 29

What is a tumour? (2 marks)

Answer 29

A large mass of cells with uncontrolled mitosis