MUST LEARN

Question 1

Difference in structure/roles between globular and fibrous proteins

Answer 1

Fibrous: structural roles
-elastic, tough , elongated, flexible, cannot stretch
-insoluble
Globular: metabolic roles
-spherical, tertiary structure, contain prosthetic group
-soluble

Question 2

What makes a protein conjugated

Answer 2

Contains a prosthetic group

Question 3

Function of fibrous proteins

Answer 3

Protection- nails, hair skin
Structure- Connective tissue , bone
Elastic- blood vessels
Contraction- muscles, cytoskeleton

Question 4

Function of gobular proteins

Answer 4

Catalyse reactions hormones e.g. insulin
Antibodies
Transport substances across cell membranes
Transport substances in the blood, haemoglobin

Question 5

How does co2 move around the body

Answer 5

5% stays in blood plasma
95% diffuses into red blood cells
15-20% binds to hb, forming carbaminohaemoglobin
75-85% forms carbonic acid, catalysed by carbonic anhydrase
Carbonic acid dissociates into h+ and hco3-
Hco3- moves out of the rbc and cl- moves in due to difference in concentration gradients
H+ is removed by buffers, haemoglobin
oxygen dissociates under h+ influence

Question 6

Process of active transport

Answer 6

Molecule or ion to be transported binds to receptor in the channel of the carrier proteins on the outside of the cell
On inside ATP binds to carrier protein and is hydrolysed into ADP + phosphate
Binding of the phosphate molecule to the carrier protein causes the protein to change shape, opening the inside of the cell
Molecule is realised to the inside of the cell
Phosphate molecule is released from the carrier protein and recombined with ADP to form ATP
carrier protein returns to normal shape

Question 7

3 domain system

Answer 7

Domains - Bacteria, archea, eukarya
Eubacteria - bacteria
archea bacteria - archea
Protocista, animlia , plantae , fungi - eukarya
Prokaryotae spilt into bacteria and archea

Question 8

How does
H+ move out of the companion cell
Sucrose move into the companion cell
Sucrose move out

Answer 8

Active transport
Facilitated diffusion
Diffusion

Question 9

How does amount of h+ effect ph

Answer 9

High concentration of h+ = low ph

Question 10

Prokaryotae

Answer 10

Unicellular
No nucleus or membrane bound organelles
ring of Naked DNA
Nutrient absorbed through cell wall or photosynthesis

Question 11

Protoctista

Answer 11

Unicellular 
membrane bound organelles 
Chloroplasts  
Some move by cilia or flagella some don’t 
Autotrophic- photosynthesis 
Heterotrophic feeders- ingestion

Question 12

Fungi - composition

Answer 12

Uni or multicellular 
Membrane bound organelles 
Cell wall of chitin 
No chloroplasts or chlorophyll
No locomotion 
Made from mycelium or hyphae
Nutrients from decaying matter, saprophytic feeders 
Store food as glycogen

Question 13

Plantae

Answer 13

Multicellular 
Membrane bound organelles 
Contain chlorophyll 
Do not move, apart from gametes 
Photosynthesis- autotrophic 
Store food as starch

Question 14

Animlia

Answer 14

Multicellular 
Membrane bound organelles 
Move by cilia or contraction of muscles 
Heterotrophic feeders 
Store food as glycogen

Question 15

What are co factors

Answer 15

Non protien helper component
Transfer atoms or groups from one reaction to another in a multi step pathway
If co factor is organic it is called a co enzyme

Question 16

Prosthetic groups

Answer 16

Are co factors Tightly bound to certain enzymes, needed to help carry out catalytic function, they form a permeant feature

Question 17

How does gas exchange take place in insects

Answer 17

Happens through spiracles which are opened and closed by sphincters
When o2 demand is high or co2 levels are high spircales open
Collapsable trachea or air sacs which act as a reservoir, to increase air movement, pumped by the abdomen ( mechanical ventilation)

Question 18

Interactions in tertiary structure

Answer 18

Further folding or coiling of secondary structures bring different amino acids close enough tighter to interact
Hydrophilic or hydrophobic between r groups - weak
Hydrogen bonds - weakest
Ionic bonds - strong
Disulphides bridges- strongest *( only r groups that contain sulphur)

Question 19

Quaternary structure

Answer 19

Association of 2 or more or protien subunits
Same interactions as tertiary
Hydrophilic or hydrophobic between r groups - weak
Hydrogen bonds - weakest
Ionic bonds - strong
Disulphides bridges- strongest *( only r groups that contain sulphur)

Question 20

Diseases caused by viruses

Answer 20

HIV
Influenza
TMV

Question 21

Diseases caused by fungus

Answer 21

Athletes foot - human
Ringworm- human , patch on skin
Potato blight -plant
Black sigatoka- plant

Question 22

Diseases caused by protoctist

Answer 22

Malaria- human, spread by female Anopheles mosquito

Question 23

Diseases caused by bacterium

Answer 23

Tuberculosis
Meningitis
Ring rot

Question 24

Structures in xylem and phloem

Answer 24

Xylem - lignified, wide lumen , no end walls, no compaion cells, vessels, bordered pits not cytoplasm
Phloem- not lignified ( contain cellulose), lumen not wide, sieve plate elements, companion cells, no vessels , no pits, has cytoplasm

Question 25

How to observe the gas exchange system of insects or fish

Answer 25

Remove operculum
Cut open exoskeleton
To observe gills or tracheae

Question 26

Translation

Answer 26

mRNA binds to small unit on ribosome
tRNA molecule with anticodon that is complementary to the start codon carries the corresponding amino acid to the ribosome
Ribosome reads the next triplet of bases on the mRNA
Another tRNA with the complementary rna nucleotides comes and binds with the 3 complementary bases, bring with it an amino acid
RNA polymerase catalyses the formation of peptide bonds between the 2 amino acids

Question 27

Transcription

Answer 27

DNA helicase unzips the 2 strands of DNA by breaking the hydrogen bonds between the bases
Free rna nucleotides bind the complementary base pairs of the template strand
Thymine is replaced with uracil
Phosphodiester bonds are formed, catalysed by RNA polymerase
mRNA strand detaches from sense strand and leaves the nucleus