module 2

Question 1

how does a compound light microscope work

Answer 1

objective lens and eyepiece lens

combination of the two allows for higher magnification and reduced chromatic aberration

Question 2

what is the difference between preparing a dry mount and a wet mount

Answer 2

dry mount
specimen placed on centre of the slide and place cover slip over the sample

wet mount
cover slip is placed on at an angle

Question 3

what do we do to wet mounts

Answer 3

squash slides

smear slides

Question 4

why are electron microscopes better than light

Answer 4

electrons have a smaller wavelength than light waves

Question 5

what is the resolution and max mag of a TEM

Answer 5

res = 0.5nm

max mag =

Question 6

what is the resolution and max mag of a SEM

Answer 6

res = 3-10nm

max mag =

Question 7

define an artefact

Answer 7

visible structural detail caused by processing the specimen

Question 8

describe the function of DNA helicase

Answer 8

unwinding and separation of DNA double helix

Question 9

describe the function of DNA polymerase

Answer 9

catalyses the formation of phosphodiester bonds between nucleotides

Question 10

what are the characteristics of DNA

Answer 10

universal

degenerate

triplet

non-overlapping

Question 11

what does the degenerate code mean

Answer 11

many amino acids can be coded for by more than one codon

Question 12

describe the ‘fluid mosaic’ model

Answer 12

phospholipids are free to move within the layer relative to each other

proteins embedded in the bilayer

Question 13

define glycoprotein

Answer 13

branched carb portion of a protein that acts as a recognition site for chemicals

Question 14

define glycolipid

Answer 14

acts as a recog site

Question 15

define intrinsic proteins

Answer 15

proteins embedded through both layers of a membrane

have hydrophobic R-groups on their surface which interact with hydrophobic core of membrane, keeps them in place

Question 16

give two examples of intrinsic proteins

Answer 16

channel proteins

carrier proteins

glycoproteins

glycolipids

Question 17

describe channel protiens

Answer 17

provide hydrophilic channel allowing diffusion of polar molecules and ions

Question 18

describe carrier proteins

Answer 18

role in passive and active transport

involves protein shape changing

Question 19

define extrinsic proteins

Answer 19

present in one side of the bilayer

have hydrophilic R-groups

Question 20

what are the 2 factors affecting membrane structure

Answer 20

temperature

solvent

Question 21

how does temperature affect membrane structure

Answer 21

phospholipids have more kinetic energy and move more

membane more fluid

Question 22

how do solvents affect membrane structure

Answer 22

many organic solvents less polar than water

organic solvents dissolve membrane

or they can disrupt the membrane (making it more fluid and permeable)

Question 23

how do neuronal membranes become disrupted by alcohol and what is the effect

Answer 23

alcohol molecules between the phospholipid disrupts the permeability of the membrane

nerve impulses can’t be normally transmitted

Question 24

how can scientists observe the route taken by a dye through the stem

Answer 24

cutting series of sections at intervals along stem

transverse sections

taking from above and below site of injection

using a microscope

Question 25

how does high light intensity require more water than shaded plants

Answer 25

high light intensity increases rate of photosynthesis more stomata open to allow gas exchange high light intensity increases transpiration so more water vapour is lost

Question 26

how would you use a colorimeter

Answer 26

zero the colorimeter use known concentration of solutions plot calibration curve measure absorance of unknown sample compare absorbance of sample with calibration graph use appropriate filter for the colour

Question 27

what is human therapeutic cloning

Answer 27

DNA of embryo is replaced with the DNA from patient

Question 28

describe uses of stem cells for research

Answer 28

grown into different tissues to test effectiveness of new medicinal drugs and side effects

Question 29

how does a bud form

Answer 29

nucleus divides by mitosis cell swells on one side nucleus, cytoplasm and organelles move into bud bud pinches off cell wall forms so bud becomes separate cellw

Question 30

what is the type of speciation that occurs when two populations live in the same location

Answer 30

sympatric

Question 31

what is allopatric speciation

Answer 31

where populations become geographically isolated from each other to an extent that prevent or interferes with gene flow

Question 32

describe the importance of the cytoskeleton

Answer 32

provides strength and stability determines shape movement of organelles holds organelles in place make up centrioles and spindle fibres

Question 33

what are adaptations of guard cells

Answer 33

large vacuole take up lots of water lots of mitochondria thicker inner wall allows bending

Question 34

what are factors of transpiration

Answer 34

light intensity wind speed humidity temperature

Question 35

what is the ACFOR scale

Answer 35

qualitative abundant common frequent occasional rare

Question 36

how can we increase reproducibility

Answer 36

use std procedure sample at different times/weather sample many times then calc mean