Biology paper 3

Question 1

Define niche

Answer 1

functional role of an organism in its habitat

Question 2

What may occur when species share the same niche

Answer 2

they will compete with each other for the same resources

One of the species will be more successful and out-compete
the other species until only one species is left and the other is either forced to occupy a new, slightly different niche or to go extinct from the habitat or ecosystem altogether

Question 3

examples where two species tried to occupy the same niche

Answer 3

speciesoccupy the same habitat (spruces and other conifer trees) but occupy slightly different niches as each species feeds at a different height within the trees
This avoids competition between the three species, allowing them to co-exist closely with each other in the same habitat

Question 4

Species definition

Answer 4

Group of living organisms that are reproductively isolated and capable of producing fertile off spring. They are anatomically, behaviourally and physiologically similar.

Question 5

3 types of adaptations

Answer 5

Anatomical - structural features such as horns, claws or feathers, that increase an organism’s chances of survival

Behavioural - behaviours such as courtship of defensive behaviours, that increase an organism’s chances of survival

Physiological, which refers to processes inside the body, such as venom production or the ability to digest cellulose, that increase an organism’s chances of survival

Question 6

examples of behavioural, anatomical and physiological adaptations in sloths

Answer 6

Moving slowly, long alimentary canal/gripping claws/enzymes to break down lactic acid

Question 7

how can mutations give rise to evolution

Answer 7

Variation caused by mutation, selection pressure, advantageous allele causes some individuals to survive and reproduce, allele passed to offspring, allele frequency increases in the population.

Question 8

importance of amino acid sequence in protein structure

Answer 8

forms the primary structure of the protein/polypeptide. R groups allow bonds to form to hold tertiary structure in place.

Question 9

how can organisms be held in taxonomic groups

Answer 9

idea that organisms with {
specific / particular / shared /
common / similar / eq} {
characteristics / features/ traits / eq } are placed in a group;
2. detail of how characteristics assessed, e.g. observable characteristics, behavioural similarities, similarities in DNA, molecular phylogeny;

Question 10

limitation of using 5 kingdom

Answer 10

virus not included

Similar organisms are kept far from each other. For example- Unicellular and multicellular algae.

based on physical characteristics

Question 11

Explain the change in classification that occurred in 1990 as a result of the work of Carl Woese

Answer 11

Based on the evidence that molecular phylogeny provided, it was determined that the organisms in the kingdom Prokaryotae would be reclassified into two separate domains - the Archaea and Bacteria

The evidence suggested that archaea and bacteria are less closely related to each other than scientists originally thought

Organisms from the other four kingdoms where placed in another domain - Eukaryota

Previously classification was based on physical features

Question 12

what is molecular phylogeny

Answer 12

similarities or differences of molecules (such as DNA, RNA or proteins) between groups of organisms to determine how closely related they are

Question 13

what is phylogeny

Answer 13

evolutionary history of different groups of organisms and can specify how closely related they are

Question 14

Carl Woese proposed a 3 domain classification system. Name the 3 domains

Answer 14

The Archaea, Bacteria and Eukaryota

Question 15

Describe how Woese work is critically evaluated

Answer 15

scientific findings published e.g. in a journal
2. idea of presented at scientific conference / eq;
3. idea of peer review;
4. (other scientists) repeat experiments (to confirm or validate findings / test reliability of data)

Question 16

Woese suggested that organisms could be placed into taxonomic groups based on molecular Phylogeny. Explain what is meant by this statement.

Answer 16

idea that organisms with { specific / particular / shared / common / similar eq > < characteristics / features / traits / eg } are placed in a group ;
2. idea that taxonomic groups have specific differences ;
3. idea that phylogeny describes {evolutionary / genetic} relationship;
4. idea that molecular phylogeny based on similarities in { DNA / DNA sequence / proteins / eq ≥

Question 17

List the sequence of taxa used in the Linnaeus classification system.

Answer 17

Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 18

Compare and contrast an algae cell with that of an animal cell

Answer 18

Chloroplasts, cell wall and vacuole only found in algae. Both eukaryotic with nucleus, plasma membrane, cytoplasm, mitochondria and ribosomes. Both can have flagella in some cases.

Question 19

Which kingdom do the 4 phyla of algae belong to?

Answer 19

Protist

Question 20

Suggest a ‘trace element’ that algae may provide for sloths

Answer 20

Fe, Zn, Cu Co, I

Question 21

describe the structure of cellulose microfibril

Answer 21

cellulose is a polymer of beta glucose (1)
* (the glucose molecules are) held together by glycosidic bonds
(1)
* -glucose monomers form (long) straight chains (1)
* (the cellulose molecules are) held together by hydrogen bonds
(1)
* microfibrils are composed of many cellulose molecules

Question 22

describe structure of cellulose cell wall

Answer 22

1. cellulose (molecule) is a { polymer / chain / eq } of
   B-glucose / eq;
2. cellulose molecules held together { by hydrogen bonds / as microfibrils }
3. idea of arrangement of microfibrils in { parallel / net / mesh / criss cross / eq ≥ ;
4. reference to { matrix / hemicelluloses /pectin / eq }

Question 23

explain how structure and properties of starch are related to its function as a storage molecule

Answer 23

contains glucose needed for {respiration/energy} (1)
* insoluble so < has no osmotic effect / remains in the cell }
(1)
* amylose is coiled making starch compact (so more can be stored)
(1)
* amylopectin {is branched/contains 1-6 glycosidic bonds} so is rapidly hydrolysed

Question 24

what disease causing protist causes malaria

Answer 24

Plasmodium

Question 25

Describe structure of an antibody

Answer 25

Y shaped protein. Heavy and light strands, cross-bridges, variable region. Quaternary protein structure

Question 26

What cells produce antibodies

Answer 26

Plasma cells . B cells

Question 27

how vasoconstriction and vasodilation keep body temperature in a narrow range

Answer 27

During vasoconstriction the muscles in the arteriole walls contract, causing the arterioles near the skin to constrict and allowing less blood to flow through skin capillaries
Instead, the blood is diverted through shunt vessels, which are deeper in the skin and therefore do not lose heat to the environment

Arterioles have muscles in their walls that can relax or contract to allow more or less blood to flow through them
During vasodilation these muscles relax, causing the arterioles near the skin to dilate and allowing more blood to flow through skin capillaries

Question 28

which part of brain responsible for vasoconstriction and vasodilation

Answer 28

Medulla oblongata

Question 29

how shivering enable body temperature of 38 degrees

Answer 29

The hair erector pili muscles in the skin contract, causing hairs to stand on end
These muscles can be described as effectors, as they respond to a change in body temperature
This means they form form an insulating layer of trapped air,heat can therefore not leave by radiation
This is a reflex action in response to a decrease in core body temperature
Nervous control
The metabolic reactions required to power this shivering generate sufficient heat to warm the blood and raise the core body temperature

Question 30

how brain reduces activity of sweat glands after exercise

Answer 30

thermoreceptors detect a decrease in temperature (1)
* {hypothalamus / thermoregulatory centre } sends fewer impulses to sweat glands

Question 31

what is a tendon

Answer 31

Joins muscle to bone

Question 32

define fatigue in terms of muscular contraction

Answer 32

Decreased ability to produce force i.e. weakness due to lower ATP production, build up of lactate due to anaerobic respiration

Question 33

Compare and contrast fast and slow twitch muscle fibres

Answer 33

Slow Twitch fibres – for endurance; Red (contain much myoglobin); Many mitochondria; Little sarcoplasmic reticulum; Low glycogen content; Numerous capillaries; Fatigue resistant

Fast twitch fibres – for sprinting; White (little myoglobin); few mitochondria; Much sarcoplasmic reticulum; High glycogen content; Few capillaries; Fatigue quickly

Question 34

reactant and product of anaerobic respiration and where does it occur

Answer 34

Glucose + 2ADP +2Pi 􏰀 2ATP + 2 lactate

Cytoplasm

Question 35

community

Answer 35

A group of different species found in an ecosystem or habitat.

Question 36

Describe the role of ‘secretions on the sloth’s skin’ in preventing pathogenic infection in the sloth.

Answer 36

Anatomical, chemical barrier. Sebum makes skin oily, skin flora outcompetes pathogen micro-organisms so they don’t have enough resources and die.

Question 37

Lactate (lactic acid) can build up in the muscles of a sprinter.
Suggest why the build-up of lactate may prevent any further increase in speed.

Answer 37

(lactate build up) causes {drop in pH / more acidic / increase H* /eq);
2. idea of this affects enzyme (activity / shape / eq] ;
3. this slows down {glycolysis / ATP production / anaerobic respiration / eg
4. reference to muscle contractions being affected;

Question 38

Explain the fate of lactic acid after a period of anaerobic respiration.

Answer 38

reference to lactate in the blood / eg;
{transported to / broken down in / eq] liver;
lactate is {converted to pyruvate / eq) ;
this involves oxidation / production of reduced NAD /
eq);
pyruvate is then foxidised / eq);
reference to Krebs cycle;
{this requires extra oxygen / reference oxygen debt} /
eg
idea that carbon dioxide and water are produced;

Question 39

Explain the importance of removing lactic acid.

Answer 39

Lactic Acid lowers pH. Enzymes denatured/ reduced activity. Less successful collisions/less enzyme substrate complexes. Directly impacts metabolic rate.