BY2 June 2012 Flashcards
(26 cards)
Characteristics - heterotrophic, multicellular eukaryotes, no cell wall, nervous coordination.
Animalia
Characteristics - eukaryotes, single celled, no tissues differentiation.
Protoctista
Characteristics - unicellular, microscopic, no membrane bound organelles, cell wall not cellulose, cell wall made of murein.
Prokaryotae
Characteristics - multicellular eukaryotes, photosynthetic, cellulose cell wall.
Plantae
State two important structural features of alveoli.
Thin alveolus walls.
Large surface area.
Briefly explain how inspiration is brought about.
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.
Define the term parasite and give an example.
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
Define the term autotroph and give an example.
Organism which uses simple inorganic molecules to synthesise complex organic conpounds.
E.g. Plant (algae)
Define the term saprobionts and give an example.
Saprobionts secrete enzymes onto the food outside the body and absorb the soluble products by diffusion.
E.g. Bacteria
What is the function of the coronary blood vessels?
Supply oxygen to the heart muscle.
Explain why the bicuspid valve often has to be replaced because it ceases to work effectively and why the tricuspid rarely needs replacing.
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.
What would happen to the flow of blood if the valve was damaged?
Blood would leak back from the ventricle to the atrium.
Suggest one symptom a person with a failing bicuspid valve may have.
Breathlessness/rapid or regular heartbeat
Describe 3 features of fish gills which allow them to achieve efficient gas exchange.
Large surface area for diffusion.
Thin/short diffusion pathway.
Permeable
Water is a dense medium with a low O2 content. Explain how bony fish have overcome the problems of O2 uptake in water.
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.
Describe two features associated with epithelial cells and explain why each is important for the cell to function efficiently.
Microvilli-increased SA for diffusion.
Mitochondria-synthesis of ATP for active transport.
Goblet cells are vital to the functioning of the intestine. Explain their function.
Secretes mucus.
Heather lives in a dry, windy environment. State 3 features a heather leaf would have.
Has a reduced SA.
Thick cuticle.
Curled downwards with the stomata inside.
Explain how having a curled leaf with the stomata inside helps the heather live in a dry environment.
Trapping water vapour so reduces water loss.
What name is given to plants that live in a dry environment?
Xerophyte.
Explain the role of xylem in the plant.
Transports water and minerals.
Explain the role of phloem in the plant?
Transports the products of photosynthesis.
Explain how the endodermis cell carries out it’s function in the uptake of water and minerals in the plant.
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.
Distinguish between the two types of reproduction used by organisms and state the advantages an disadvantages of each.
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.
