Final set flash cards
Outline the mechanism of sucrose loading
Hydrogen ions are pumper out of the cytoplasm of companion cells (requires ATP) into the cell wall. This creates a high concentration of hydrogen ions, so they flow back into the cytoplasm down concentration gradient via cotransporter proteins, carrying sucrose molecules with them. Sucrose can then flow into the sieve tube elements via plasmodesmata.
What are the stages involved in PCR and what is its purpose?
- Heat the DNA to 95 degrees to denature the DNA which breaks hydrogen bonds so it is single stranded
- Reduce the temperature to 55 degrees to anneal primers
- Increase temperature to 72 degrees which is the optimum temperature for Taq polymerase which joins free nucleotides in 5’ -> 3’ direction.
The purpose of PCR is to amplify DNA so it can be used for analysis.
Outline the roles of all 5 plant hormones
-Auxin - promotes cell elongation, inhibits leaf abscission, inhibits growth of lateral shoots
-Gibberellins - Promotes seed germination and growth of stems
-Cytokinins - Promotes cell division, delays leaf senescence, overcomes apical dominance, promotes cell expansion
-Absisic Acid- inhibits seed germination and growth of stems, causes stomatal closure in low water availability
Ethene - promotes fruit ripening
What are the roles of the different bacteria in the nitrogen cycle
-Nitrogen fixing bateria - convert nitrogen gas to NH4+ ions ( Rhizobium and Azotobacter)
-Nitrifying bacteria - Convert NH4+ to nitrites (NO2-) by nitrosomonas and nitrates (NO3-) by nitrobacter
-Denitrifying bacteria - Converts nitrates in the soil back into nitrogen gas
What is the role of each part of the brain (4) ?
-Cerebrum - voluntary actions, thought, speech, memory, problem solving
-Cerebellum - muscle coordination and movement and balence
- Hypothalamus - monitors blood and is involved in homeostasis
- Medulla Oblongata - involuntary actions, e.g controlling hear rate and breathing rate
