Topic 2-cell biology

Question 1

Glucose

Answer 1

Less dense than 1.9
nucleus: most dense

Question 2

Differentiating endoplasmic reticulum

Answer 2

Use smaller intervals of sucrose solution as RER is more dense

Question 3

Bacteria in antibiotic

Answer 3

-gram pos have thicker walls
-some antibiotics inhibit formation of peptidoglycan so affective in gram pos
-some can’t cross peptidoglycan layer so affective in gram neg

Question 4

Electron microscope

Answer 4

-higher resolution
-shorter wavelength
-things not too close together

Question 5

Comparing gram pos and neg

Answer 5

Both:
peptydoglycan

Pos:
-thicker peptidoglycan
-teichoic acid

Neg:
-outer membrane
-more lipids and lypoplysaccharide

Question 6

Exposure to radiation

Answer 6

-only if more than 4h
-not all species tested
-toxins still remain in food

Question 7

Stains

Answer 7

Ensure that some organelles are clearly visible

Question 8

Microscopy

Answer 8

-locate sample using low objective lens
-focus using objective lens
-fine focus with high objective lens

Question 9

Liver and pancreas comparison

Answer 9

-liver has less cell membrane as more organelles
-liver has less RER-less protein made
-more mitochondria as more metabolically active

Question 10

Golgi apparatus

Answer 10

-vesicles fuse with golgi
-proteins move Golgi in vesicles
-vesicles fuse with membrane

Question 11

lysosome

Answer 11

produce enzymes to digest old organelles

Question 12

Protein synthesis

Answer 12

-mrna leaves through nuclear pores
-to RER ribosomes
-trna brings amino acid
-peptide bonds
-enters Golgi and modified
-exocytosis

Question 13

Golgi apparatus structure

Answer 13

-membrane bound flattened sacks
-cisternae

Question 14

Crossover

Answer 14

-between chromatids
-so half of the chromosomes will be recombinant
-but doesn’t always occur

Question 15

Root tip squash improvements

Answer 15

-conc acid to separate layers of cells
-heat to intensify the effect of acid
-squash the coverslip to see individual layers of cells and prevent evaporation
-tease with needle to separate individual layers
-add stain and acid separately

Question 16

Why mitotic index is different for 2 different root tips

Answer 16

-hard to determine the correct stage of mitosis
-variation due to chance could have an effect

Question 17

Microtubulin formation

Answer 17

-centrioles are needed as microtublins didn’t grow without them
-concentration of tubulin is important
-conc affected rate as collision theory
-graph not linear so third factor involved

Question 18

Mitosis

Answer 18

-DNA replication
-sister chromatids equally distributed
-so no genetic variation

Question 19

Mitosis time practical

Answer 19

1. Prepare slide like root tip
2. Count the no. of cells in insert stage
3. Find the proportion of cells in that stage
4. Calculate time relative to 24h

Question 20

Chromosomes throughout mitosis

Answer 20

1. Chromatids join at centromere to form chromosomes
   2.DNA content returns to normal at cytokinesis as cell divides into 2

Question 21

Haploid and diploid

Answer 21

haploid-23
diploid-46

Question 22

Microtubule

Answer 22

-shortened as they would in cell division
-shortened/broken by centriole

Question 23

Colchicine

Answer 23

-No effect at interphase
-affects prophase and spindle formation

Question 24

Importance of centrioles in sperm

Answer 24

-source of centriole in zygote so it make spindle fibres for mitosis

Question 25

Importance of DNA replication

Answer 25

-Divide through mitosis
-to make identical copies of DNA so all cells are diploid

Question 26

Enzyme

Answer 26

digest through secondary oocyte

Question 27

Investigating effect of ph on pollen growth

Answer 27

-5 diff ph
-sucrose solution
-rate of growth
-repeat+mean

Question 28

Standard deviation

Answer 28

-show variation from mean
-indicate levels of significance

Question 29

Role of enzymes in plant fertilisation

Answer 29

-digest style tissue
-provide nutrients for pollen tube growth
-clears path for pollen tube growth

Question 30

Antibiotic in bacteria cell wall

Answer 30

-inhibit peptidolglycan formation so affective for gram pos
-can’t pass peptidoglycan so effective for gram neg

Question 31

Antibiotics on virus

Answer 31

Not a living cell and doesn’t have a cell wall

Question 32

Mitochondria

Answer 32

contains ribosomes

Question 33

Calibration

Answer 33

-eyepiece graticule to measure diameter
-calibrate using stage micrometer

Question 34

asexual reproduction advantage

Answer 34

-large no of offspring
-rapid
-don’t need another plant

Question 35

Lambda phage

Answer 35

DNA virus with complex protein capsid

Question 36

Why cell burst from virus takes time

Answer 36

-they attach to host cells and synthesise DNA
-transcription and translation
-new viruses made

Question 37

Lytic cycle

Answer 37

-Virus penetrates host cell
-viral proteins made
-virus multiply and cells burst

Question 38

Latency

Answer 38

-Virus DNA integrated into host cell
-virus is inactive
-replicate when host cell divides

Question 39

RNA virus

Answer 39

RNA and protein made

Question 40

Virus vs bacteria

Answer 40

-both have DNA
-virus hollow, bacteria has cytoplasm
-virus has capsid, bacteria has cell wall

Question 41

HIV

Answer 41

Contain RNA and reverse transcriptase

Question 42

RNA

Answer 42

all are surrounded by protein

Question 43

Lipid sap containing virus

Answer 43

-more virus delivered
-can pass through cell membrane
-protected from enzymes
(could be broken by enzymes )

Question 44

Non retrovirus

Answer 44

translation-more RNA produced