biology 01

Question 1

what is a protein

Answer 1

sequence of amino acids in a polypeptide chain

Question 2

what drug causes vasodilation?

Answer 2

antihyperintensives, lowering blood pressure and reducing risk of atheroma formation

Question 3

what does the enzyme amylase do?

Answer 3

breaks downs starch during hydrolysis

Question 4

Describe how the effect of amylase concentration on the breakdown of starch
at 23 qC could be investigated.

Answer 4

use different concentrations of amylase
observe the time ti takes for maltose to be produced
keep temperature constant using water bath at 23 degrees
use a control volume of starch

Question 5

what does it mean if a molecule is soluble or insoluble?

Answer 5

soluble means molecule is ionic and polar and cannot pass through the phospholipid bilayer as its charged so requires channel or carrier proteins but insoluble means its non polar and has no charge and can dissolve through phospholipid bilayer

Question 6

Explain the effects on red blood cells of high concentrations of sodium chloride in
blood plasma.

Answer 6

more water moves out of cells by osmosis to an area of high solute concentration this reduces volume of red blood cell.

Question 7

A dense network of capillaries covers the outside of each alveolus. how does this help with efficient gas exchange

Answer 7

provides large surface area
thin walls so short diffusion distance
carry oxygen away from alveolus and delivers carbon dioxide

Question 8

Explain how the sequence of bases in DNA determines the primary structure of a
protein.

Answer 8

dna sequence is used as template for mrna
Rna polymerase used to form complimentary base pairing
codon is made of triplet of bases of dna which then code for sequence of amino acids in polypeptide chain

Question 9

what is a source and a sink in phloem?

Answer 9

the source is a leaf which photosynthesis in summer and transports sucrose to the companion cell which contains a lot of mitochondria and unloads sucrose into phloem via plasmodesmata
the source is the root hair cell where sucrose is unloaded and stored as starch
during spring, starch is used to grow the leaves so sink is the leaves and growing buds whereas source is the roots.

Question 10

describe the mass flow system in phloem?

Answer 10

so solutes are loaded into the phloem via companion cell and plasmodesmata. this increases solute concentration which draws water in from xylem vessels via osmosis. this increases hydrostatic pressure and solute is moved along the phloem through perforated holes. then unloaded into the root cell and water moves back into xylem via osmosis and hydrostatic pressure is reduced. the pressure between the unloading and loading sites is what causes a mass flow system.

Question 11

where does active transport occur in phloem?

Answer 11

Occurs in when solutes are loaded into phloem sieve tubes

Question 12

what does the hydrostatic pressure in plants cause?

Answer 12

this causes the organic solutes such as sucrose to move along the phloem sieve tube.

Question 13

where does active transport occur in the plant?

Answer 13

when inorganic ions are released into the root cell, active transports used

Question 14

what is the difference between plant cell and an animal cell?

Answer 14

plant cell contains a cell wall and chloroplast.

Question 15

what is amyloplast?

Answer 15

they are found in plants and store starch grains. starch is broken down to use this energy in source for growing leaves or buds.

Question 16

how does water move in and out of cells?

Answer 16

through pits in walls with no lignin

Question 17

describe the structure of starch?

Answer 17

amylose-1-4 glycosidic bonds and coil into a spiral shape.

amylopectin- 1-6 and 1-4 branched. storage molecule.

Question 18

state 3 differences between plant and animal cells?

Answer 18

plant cells are larger than animal cells 10-100 micrometres whereas animals are 10-30 micrometres
plant cells have vacuole containing enzymes whereas animals have lysosomes containing lysozyme as digestive enzymes

Question 19

what is species diversity?

Answer 19

number of different species living in an area

Question 20

what reduces species diversity?

Answer 20

anthropogenic causes such as deforestation

Question 21

what do the Q and P stand for in hardy Weinberg?

Answer 21

q is homozygous recessive and p is homozygous dominant.

Question 22

describe the process of natural selection

Answer 22

for natural selection there must be genetic variation, an allele can be neutral but become selectively very advantageous when the environment changes
chnage in allele frequency over time
1) naturally occurring genetic variation mutations give rise to new alleles
2) chnage in the environment causes a chnage in selection pressure
allele become advantageous
organisms with that allele more likely to survive and reproduce
increasing gene pool

Question 23

what is a gene pool?

Answer 23

complete set of alleles for all the genes present in a population

Question 24

what does the ability of the population to adapt depend on?

Answer 24

strength of selection pressure, size of gene pool, the reproductive rate of the organism, reproductive isolation causes speciation, change in allele frequency means a change in phenotype so cannot reproduce to produce fertile offspring

Question 25

what are the 3 domains?

Answer 25

eukarya, archaea, bacteria

Question 26

what do phylogenetic diagrams show?

Answer 26

evolutionary relationship between organisms based on molecular differences. distance between ancestor and species shows how closely related they are.

Question 27

suggest one environmental advantage of using biodegradable plastic?

Answer 27

can be decomposed, will not accuumlate,

Question 28

how do captive breeding programmes help conserve genetic diversity?

Answer 28

use of studbooks, prevent genetic drift and inbreeding depression, selecting mates, increasing population of species, species that have low genetic diversity and small gene pool.