Paper 3 Cram Flashcards
How does gas exchange occur in fish?
Ventilation begins with the fish opening its mouth followed by lowering the floor of buccal cavity, thus enabling water to flow into it. Afterwards, fish closes its mouth, causing the buccal cavity floor to raise, thus increasing the pressure. The water is forced over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity. The operculum acts as a valve and pump and lets water out and pumps it in.
Hormones released from the adrenal medulla
The adrenal medulla releases the adrenaline and noradrenaline hormones
Hormones released from the adrenal cortex
The adrenal cortex releases steroid hormones. This includes glucocorticoids, mineralcorticoids and androgens.
Role of glucocorticoids
Glucocorticoids regulates glucose and protein metabolism, as well as supression of the inflammatory response
Role of mineralcorticoids
Mineralcorticoids maintain salt concentrations to control blood pressure.
What’s the difference between coenzymes and cofactors?
Cofactors = inorganic ions that aid enzyme function
Coenzymes = organic ions that are derived from vitamins
Examples of human cells specialised for their functions
→ Erythrocytes → Biconcave shape (increased surface area to volume ratio to transport more oxygen), No nuclei (more space for haemoglobin), flexibility (move through capillaries)
→ Neutrophils → multi-lobed nucleus → fit through gaps to reach sites of infection
→ Sperm → flagella for movement, lots of mitochondria for ATP supply
→ Squamous epithelium → flat for increased diffusion
→ Cilliated epithelium → contains goblet cells which release mucus that traps pathogens
→ Cartilage (connective tissue) → prevents ends of bones rubbing and causing damage
Plant cell examples that are adapted to their functions
→ Palisade cells in plants → thin walls for diffusion and large vacuoles to maintain turgor pressure
→ Root hair cells → root hairs increases surface area to increase water uptake through the roots of the plant
→ Guard cells in stomata → can change shape to prevent excessive water loss, has a thicker cell wall one side to prevent symmetrical shape change
→ Epidermis → found on plant surface and contains the stomata, contains waxy cuticle which helps prevent excessive water loss in plants
→ Xylem → contatains lignin for strength
→ Phloem → transports sucrose via mass flow
What is tidal volume?
Tidal volume = maximum volume of air in a normal resting rbeath
How to calculate pulmonary ventilation rate?
Pulmonary ventilation rate = tidal volume x breathing rate
What are the different structures found within the liver and their functions?
→ Hepatocytes = main liver cell which divide and replicate
→ Sinusoids = spaces between hepatocytes where blood from hepatic artery and portal vein mixes
→ Kupfer cells = macrophages
→ Canaliculi = spaces where bile is secreted and then drained into ductules
→ Hepatic artery = Supplies the liver with oxygenated blood
→ Hepatic portal vein = supplies blood rich in products for metabolism
→ Hepatic vein = supplies the liver with deoxygenated blood
→ Bile duct = transports bile to gall bladder
→ Gall bladder = bile is stored then released into small intestine
→ Ligaments seperates liver lobes
What are the primary non-specific animal defences against pathogens?
→ Skin (secretes sebum that inhibits pathogen growth)
→ Mucous from globet cells
→ Lysosomes in tears and urine
→ Stomach acid
→ Blood clotting (platelets clump at broken vessel and adhere, thrombrin + fibrin released that helps clot)
→ Fever
→ Inflammatory response
→ Phagocytosis
What is the action of the inflammatory response?
Inflammatory response:
→ Inflammation localised and results in pain, swelling and redness
→ Histamines released which causes vasolidation → temperature increase, plasma forced out (swelling)
→ Cytokines attract phagocytes
What are baroreceptors?
Baroreceptors are pressure receptors. They are sensitive to blood pressure. Too high = impulses sent to medulla oblongata centre which decreases HR (impulses sent along parasympathetic neurones to SAN) and vice versa.
What are chemoreceptors?
Chemoreceptors detect changes in chemical levels. They are sensitive to pH level of blood (CO2 increase = pH decrease due to carbonic acid) → heart rate increased to increase blood flow
How does pregnancy tests work?
1 → Wick soaked in urine (highest hCG levels)
2 → Monoclonal antibodies beads attach only to hCG
3 → 2nd set of monoclonal antibodies are immobolised so binds to hCG complex regardless.
Outline the action of giberellin/germination
1 = Seed absorbs water
2 = Embryo activated
3 = Giberellins stimulate enzymes to break down food stores
4 = ATP produced → ABA works againsts giberellins to determine when the seed germinates.
How auxins stimulate apical growth?
1 = Auxins synthesised in meristems
2 = Auxins diffuse away from tip or shoot
3 = Auxins ind to cell receptors
4 = Vacuoles form and pH lowers > optimum conditions for expansin enzyme
5 = Expansins break down cell wall to increase flexibility and vacuoles can absorb more water
6 = Auxin destroyed and cell wall of vacuole becomes rigid
What are the commercial uses of plant hormones?
→ Ethene used to control fruit ripening, exposed to to ethene gas so all plants ripen at same rate
→ Hormone rooting powders → ease of propogation
→ Auxin → seedless fruit
→ Giberellins → delays ripening and ageing of fruit
Outline the process of transcription and translation of DNA
1). DNA helicase breaks H bonds between complementary bases
2). Free nucleotides bind to the exposed bases on the antisense strand
3). RNA polymerase forms phosphodiester bonds between nucleotides and mRNA detaches
4). mRNA binds to subunits of ribosome
5). Anticodons on tRNA binds to mRNA codons, forming the amino acid sequence
DNA replication
1). Helicase seperates DNA strands
2). Free nucleotides bind to exposed bases and are lined up via DNA polymerase
Active transport across membranes
1). Moleculebinds to receptors of carrier proteins
2). ATP binds to the carrier protein (and is hydrolysed)
3). Protein changes shape and molecule gets released inside
Gillventilation
1). Buccal cavity lowered -> volume increasesand pressure decreases -> causing water to move in
2). Operculum cavity expands, lowering pressure and causing water to move in and then across the gills
Translocation in the phloem
Translocation in the phloem:
1). Sucrose enters via active loading
2). Facillitated diffusion of hydrogens bring sucrose into the companion cells, creating a gradient
3). Sucrose enters sieve tube elements, water follows by osmosis and hydrostatic pressure increases
4). Assimilated move from source to sink via mass flow
Sliding filament model
Sliding filament model:
1). Action potential arrives at neuromuscular junction and sodium ion channels open
2). Calcium released from sarcoplasmic reticulum and binds to troponin, changing its shape
3). Troponin is displaced from myosin binding sites
4). Myosin and actin form cross-bridges
5). Myosin sweeps actinalong, sarcommere shortening in length
6). ATP binds to myosin head which causes it to detach frmoactin
Stomatal control by ABA
Stomatal control by ABA:
1). Roots detect water abiotic stress
2). ABA released and binds to stomata receptors
3). Ionic concentration change in guard cells
4). Water potential reduced and cells close stomata
