Potential Essay Questions

Question 1

Q: The importance of movement in living organisms

Answer 1

1. DNA Replication - Complementary base pairs, DNA Helicase unzips, template, nucleotides attach to exposed bases, condensation, DNA polymerase re-zips
2. Control of Heart Rate - Myogenic, impulses from Medulla Oblongata, delay at the AVN, Sympathetic, receptors detect a need for increase in HR
3. Control of Blood Glucose - Pancreas > islet of Langerhans, receptors detect change, a-cells produce Glucagon to increase and b-cells produce Insulin to decrease. TOO HIGH = water moves into blood, increases pressure which can lead to heart attack if unattended. TOO LOW = lowers pressure in blood, lack of glucose for respiration
4. Gas Exchange in Humans - lungs, ventilation/circulation, alveolar epithelium > capillary endothelium, diffusion gradient, supply of O2, removal of CO2 to prevent lactic acid build up/anaerobic

Question 2

Q: The importance of receptors in living organisms

Answer 2

1. Synaptic Transmission - calcium ion channels open, calcium ions to diffuse into Synaptic Knob, stimulates release of ACh into Synaptic Cleft, Neurotransmitters (Ach) bind to RECEPTORS on sodium ion channels so they open and NA+ ions diffuse into the post synaptic cell = depolarization > if threshold is reached action potential will occur
2. Cell Recognition/The Immune System - T-cells have RECEPTORS on its surface that bind to complementary antigens presented to it by phagocytes
   = Helper t-cells (release chemical signals that stimulate phagocytes) or Cytotoxic t-cells (kill abnormal and foreign cells)
   > Cellular response
3. . Control of Heart Rate - Myogenic, impulses from Medulla Oblongata, delay at the AVN, Sympathetic, RECEPTORS (e.g. chemoreceptors) detect the need for increase in HR
4. Hormones/Homeostasis - adrenaline (from adrenal glands) attaches to RECEPTOR site on the liver cell, activates enzyme Adenylate Cyclase, converts ATP to cyclic AMP (aka. cAMP), activates enzyme Protein Kinase A, breaks down glycogen > glucose (needed if glucose levels are low)

Question 3

Q: The control of processes in cells and the importance of these controls

Answer 3

1. Photosynthesis - LDR = photoionisation, ATP and reduced NAD produced for the LIR. Photophosphorylation (ETC) and photolysis (water into protons, oxygen and electrons). LIR = Calvin Cycle: RuBP + CO2 > G-3-P > TP
2. Gene expression - Transcription factors bind to promotors so RNA Polymerase can attach, mRNA is made. RNAi can cut up mRNA into two so it can no longer be transcribed. Oestrogen changes shape of the transcriptional factor so inhibitor molecule no longer fits so transcriptional factor can bind to specific base sequence in DNA promotor, increasing transcription
3. Control of Blood Glucose - Pancreas > islet of Langerhans, receptors detect change, a-cells produce Glucagon to increase and b-cells produce Insulin to decrease. TOO HIGH = water moves into blood, increases pressure which can lead to heart attack if unattended. TOO LOW = lowers pressure in blood, lack of glucose for respiration
4. Passage of water through a plant -
   PHLOEM = SOURCE: companion cells > sieve tubes by active transport to lower water potential so water moves in by Osmosis creating a HIGH pressure.
   SINK: opposite, as solutes being used up , lowers pressure so causes a pressure gradient allow movement of substances.
   XYLEM = evaporation through stomata, reduces water potential, replace water, negative pressure at the top, water molecules have cohesion, pulled up in continuous column, inward pull/adhesion occurs

Question 4

Q: The importance of proteins in the control of processes and responses in organisms

Answer 4

1. Proteins/Enzymes in Photosynthesis - during photophosphorylation, ATP SYNTHASE is needed to allow protons to diffuse back into the stroma across the thylakoid membrane and the energy from this movement combines ADP + Pi to make ATP ( which is important for energy needed to reduce G-3-P in LIR). During the Calvin Cycle, RuBisCo enzyme is needed to combine CO2 and RuBP to from G-3-P
2. Control of Movement across membranes - intrinsic and extrinsic proteins (carrier and channel) allow large, polar molecules to cross the membrane via facilitated diffusion and Active Transport. This is important in Co-transport of sodium ions + glucose (e.g. co-transporter proteins) > lumen into epithelial cell + glucose > glucose then diffuses into blood via channel protein
3. Gene expression - Transcription factors bind to promotors so RNA Polymerase can attach, mRNA is made. RNAi can cut up mRNA into two so it can no longer be transcribed. Oestrogen changes shape of the transcriptional factor so inhibitor molecule no longer fits so transcriptional factor can bind to specific base sequence in DNA promotor, increasing transcription
4. Synaptic Transmission - calcium ion channels open, calcium ions to diffuse into Synaptic Knob, stimulates release of ACh by into Synaptic Cleft, Neurotransmitters (Ach) bind to RECEPTORS on sodium ion channels so they open and NA+ ions diffuse into the post synaptic cell = depolarization > if threshold is reached action potential will occur