plants exam prep

Question 1

how do you measure the size of an object under a microscope?(3)

Answer 1

-measure with an eyepiece graticule
-calibrate with the stage micrometer
-repeat and calculate an average

Question 2

give two factors which affect the ability of bacteria to cause disease(2)

Answer 2

-invasiveness
-site of infection

Question 3

labelled antibodies and electron microscope can be used to produce images locating proteins on the surface of organelles, but cannot be used to observe cross bridge cycling on muscle cells. explain why. (4)

Answer 3

-em gives high resolution
-due to short wavelength of electrons
-electron must pass through a vacuum
-so material must be dead

Question 4

explain how viruses cause damage to cells (4)

Answer 4

-digests hosts genetic material
-virus DNA inserted into hosts DNA
-viral proteins synthesized by hosts cells aa
-cell lysis

Question 5

define resolving power and state why it is better for em than light (2)

Answer 5

-ability to distinguish points
-electrons have shorter wavelengths

Question 6

palisade cells are the main site of ph/s. explain one way in which a palisade cell is adapted for ph/s. (6)

Answer 6

1. there are lots of chloroplasts that can move
2. can absorb lots of light
3. palisade cells are elongated so
4. light has a longer pathway allowing maximum light absorption
   5.can absorb a range of wavelengths for max abs

Question 7

explain the advantages and limitations of using a TEM to investigate cell structure compared to an optical microscope(6)

Answer 7

advantages: 1.small objects can be seen bc 2. TEM has a high resolution bc 3. wavelength od lectrons is shorter
limitations: 1. cannot look at living cells. 2.must be in a vacuum. 3. doesnt produce a colour image

Question 8

describe how the structure of a cholera bacterium is different from the structure of an epithelial cell from the small intestines. (6)

Answer 8

1.cb is prokaryote
2. doesn’t have nucleus
3. no membrane bound organelles
4.no mitochondria
5.small ribosomes only
6.has a flagellum

Question 9

structure of ER

Answer 9

foldeed membranes called cisternae
RER has ribosomes on the cisternae
RER: protien synthesis
SER: synthesis and storage of carbohydrates and lipids

Question 10

How does mitochondria help absorb the products of digestion (2)

Answer 10

• site on aerobic respiration
• releases energy for active transport

Question 11

describe the structure and function of the nucleus (4)

Answer 11

-has a double membrane
-has nucleolus
- function is to store and make RNA