BY2 June 2012

Question 1

Characteristics - heterotrophic, multicellular eukaryotes, no cell wall, nervous coordination.

Answer 1

Animalia

Question 2

Characteristics - eukaryotes, single celled, no tissues differentiation.

Answer 2

Protoctista

Question 3

Characteristics - unicellular, microscopic, no membrane bound organelles, cell wall not cellulose, cell wall made of murein.

Answer 3

Prokaryotae

Question 4

Characteristics - multicellular eukaryotes, photosynthetic, cellulose cell wall.

Answer 4

Plantae

Question 5

State two important structural features of alveoli.

Answer 5

Thin alveolus walls.

Large surface area.

Question 6

Briefly explain how inspiration is brought about.

Answer 6

Contraction of intercostal muscles and diaphragm.
Ribcage moves up and out and diaphragm contracts and flattens.
Increased volume and decreased pressure so air moves into lungs.

Question 7

Define the term parasite and give an example.

Answer 7

Organism that lives on or in another organism(the host) obtaining nourishment at the expense of the host, causing harm to the host.
E.g. Tapeworm

Question 8

Define the term autotroph and give an example.

Answer 8

Organism which uses simple inorganic molecules to synthesise complex organic conpounds.
E.g. Plant (algae)

Question 9

Define the term saprobionts and give an example.

Answer 9

Saprobionts secrete enzymes onto the food outside the body and absorb the soluble products by diffusion.
E.g. Bacteria

Question 10

What is the function of the coronary blood vessels?

Answer 10

Supply oxygen to the heart muscle.

Question 11

Explain why the bicuspid valve often has to be replaced because it ceases to work effectively and why the tricuspid rarely needs replacing.

Answer 11

Bicuspid valve exposed to a higher pressure in the left ventricle.
Tricuspid valve exposed to a lower pressure in the right ventricle as it pumps blood to lungs.

Question 12

What would happen to the flow of blood if the valve was damaged?

Answer 12

Blood would leak back from the ventricle to the atrium.

Question 13

Suggest one symptom a person with a failing bicuspid valve may have.

Answer 13

Breathlessness/rapid or regular heartbeat

Question 14

Describe 3 features of fish gills which allow them to achieve efficient gas exchange.

Answer 14

Large surface area for diffusion.
Thin/short diffusion pathway.
Permeable

Question 15

Water is a dense medium with a low O2 content. Explain how bony fish have overcome the problems of O2 uptake in water.

Answer 15

Water is forced over the gill by ventilation mechanisms.
Unidirectionally/one way flow.
Countercurrent flow of blood and water.
Diffusion gradient maintained over the entire gill surface.
High affinity Hb.

Question 16

Describe two features associated with epithelial cells and explain why each is important for the cell to function efficiently.

Answer 16

Microvilli-increased SA for diffusion.

Mitochondria-synthesis of ATP for active transport.

Question 17

Goblet cells are vital to the functioning of the intestine. Explain their function.

Answer 17

Secretes mucus.

Question 18

Heather lives in a dry, windy environment. State 3 features a heather leaf would have.

Answer 18

Has a reduced SA.
Thick cuticle.
Curled downwards with the stomata inside.

Question 19

Explain how having a curled leaf with the stomata inside helps the heather live in a dry environment.

Answer 19

Trapping water vapour so reduces water loss.

Question 20

What name is given to plants that live in a dry environment?

Answer 20

Xerophyte.

Question 21

Explain the role of xylem in the plant.

Answer 21

Transports water and minerals.

Question 22

Explain the role of phloem in the plant?

Answer 22

Transports the products of photosynthesis.

Question 23

Explain how the endodermis cell carries out it’s function in the uptake of water and minerals in the plant.

Answer 23

Waterproof/Casparian strip.
Blocks the apoplast pathway.
Selective uptake/transport of minerals by endodermis cells into symplast pathway.
Active transport of minerals into pericycle.
Water follows by osmosis and water and minerals move into xylem vessels.

Question 24

Distinguish between the two types of reproduction used by organisms and state the advantages an disadvantages of each.

Answer 24

Asexual and sexual reproduction.
Asexual produces offspring that are genetically identical by mitosis.
Allows rapid colonisation in favourable conditions/outcompete a sexual rep.
But if conditions change or disease occurs all individuals may die.
Sexual reproduction produces genetically different offspring.
Gametes produced by meiosis.
Genetic variability allows species to adapt to environmental change.
Slower as needs a partner.

Question 25

Explain how the reproductive strategies of flowering plants have led to their success.

Answer 25

Have a relationship with insects, relying on them for pollination.
Have a relationship with insects relying on them for see dispersal.
Pollen can survive without water.
Seed has a resistant coat to withstand adverse conditions.

Question 26

Characteristics - heterotrophic eukaryotes, cell wall of chitin, reproduce by spores.

Answer 26

Fungi