ON EXAM

Question 1

Practice question:

Scenario: Your body is exposed to extreme heat during a hot summer day, and your body temperature starts to rise above normal.

1. Identify the stimulus, sensor, integrator, effector, and desired response involved in maintaining homeostasis.
2. Describe the process your body undergoes to cool down and maintain a stable temperature.
3. Is this a positive or negative feedback loop? Explain your answer.

This question is an example to what COULD be on the exam (not exact)

Answer 1

Answer:

1. Stimulus: Increased body temperature due to heat.
   
   • Sensor: Thermoreceptors in the skin and brain.
   • Integrator: Hypothalamus in the brain.
   • Effector: Sweat glands, blood vessels (skin).
   • Desired Response: Lowering body temperature to normal levels.
2. Process to cool down:
   
   • When the temperature rises, thermoreceptors detect it and send a signal to the hypothalamus.
   • The hypothalamus sends signals to sweat glands to release sweat (which evaporates to cool the body).
   • It also signals blood vessels near the skin to dilate, allowing heat to escape through the skin.
3. Negative feedback loop:
   
   • This is a negative feedback because the response (cooling down) works to counteract the original stimulus (heat), bringing the body temperature back to normal.

Question 2

Practice question:

• You are provided with several graphs representing blood sugar levels over time during and after exercise.Graph A: Shows blood sugar levels during moderate exercise, with a slight decrease during the activity and then returning to normal after exercise.Graph B: Shows blood sugar levels during intense exercise, where blood sugar initially decreases rapidly and then increases slightly post-exercise.Graph C: Shows blood sugar levels before, during, and after exercise in a person with diabetes, where blood sugar remains elevated before and during exercise and does not return to normal after exercise.

This question is an example to what COULD be on the exam (not exact)

Explain the differences in blood sugar regulation during exercise for a person with a healthy metabolism (Graph A), someone engaging in intense exercise (Graph B), and a person with diabetes (Graph C). What roles do insulin and glucagon play in these processes?

Answer 2

• Graph A (Healthy metabolism): During moderate exercise, blood sugar levels drop slightly because muscles use glucose for energy. The pancreas releases glucagon to raise blood sugar back to normal after exercise.
• Graph B (Intense exercise): During intense exercise, blood sugar drops quickly as the body demands more energy. The pancreas releases glucagon to raise blood sugar. After exercise, the body tries to return to normal by releasing insulin to regulate sugar levels.
• Graph C (Diabetes): In diabetes, blood sugar levels remain high before and during exercise because the insulin produced by the body is not functioning properly. The body is unable to regulate blood sugar, and glucagon is not effective in maintaining balance. Post-exercise, blood sugar remains high because insulin does not properly signal cells to take up glucose.

Question 3

Practice question:

Wobble hypothesis

This question is an example to what COULD be on the exam (not exact)

Answer 3

Wobble Hypothesis (Simple Explanation):

• What is it?
  The wobble hypothesis explains why some codons (three-letter sequences in mRNA) that differ in the third base still code for the same amino acid.
• Why does it happen?
  The third position of a codon doesn’t always need to match perfectly with the tRNA’s anticodon. This “wobble” in the base-pairing allows for some flexibility, so the same amino acid can be added even if the third base of the codon is different.
• Example:
  • Codons like GCU, GCC, GCA, and GCG all code for the same amino acid (alanine), even though they have different third bases (U, C, A, G).

This flexibility helps make the translation process more efficient and reduces the impact of mutations in the third base of a codon.

Question 4

Practice question:

Oxytocin is a hormone involved in childbirth. If the posterior pituitary gland is not functioning properly and is unable to release oxytocin, how would this affect a pig’s childbirth process?

This question is an example to what COULD be on the exam (not exact)

Answer 4

Answer:
If the posterior pituitary gland is not working, it cannot release oxytocin, which is necessary for the initiation of labor and for uterine contractions during childbirth. As a result:

• Labor may be delayed or unable to start naturally.
• Uterine contractions, which help push the piglets out, would be weak or absent.
• The pig may experience prolonged labor, which can be harmful for both the pig and its offspring.
• Intervention would likely be needed to assist in the birthing process.

In summary, without oxytocin from the posterior pituitary, it would be extremely difficult for the pig to give birth, potentially leading to complications.

Bc the gland stores and releases oxytocin, it promotes childbirth and if not working it is going to inhibit that. Extremely difficult for pigs to give birth.

Question 5

Practice question:

You are stranded in a remote area with no access to oxygen, water, or food for an extended period of time. Explain how your body maintains homeostasis and survives using cellular respiration, focusing on the role of hormones like glucocorticoids and glucagon.

This question is an example to what COULD be on the exam (not exact)

Answer 5

If you were stranded without food, water, or oxygen, your body would work hard to survive. Without food, your pancreas releases a hormone called glucagon, which tells the liver to turn stored glycogen into glucose for energy. If no food is available for a longer time, another hormone, cortisol, helps break down proteins and fats to make more glucose. If oxygen is also low, your body switches to anaerobic respiration, which makes energy using lactic acid fermentation instead of oxygen. Even though this produces less energy, it’s enough to keep your body running. These processes help your body adapt and survive.

Question 6

Practice question:

explain translation or transcription in detail (3 marks)
If a certain thing did not work during one of the processes, how does it affect the process?

This question is an example to what COULD be on the exam (not exact)

Answer 6

Transcription: Transcription is the process by which a segment of DNA is copied into mRNA by the enzyme RNA polymerase. It occurs in the nucleus. During transcription, RNA polymerase binds to the promoter region of a gene and unwinds the DNA. The RNA polymerase then synthesizes a complementary strand of mRNA by adding RNA nucleotides (A, U, C, G) to the growing strand, following the base-pairing rules. This mRNA carries the genetic information from the DNA to the ribosome, where protein synthesis occurs.

Translation: Translation is the process in which the mRNA is used as a template to synthesize a protein. It occurs in the cytoplasm at the ribosome. The mRNA is read in sets of three nucleotides called codons, with each codon corresponding to an amino acid. tRNA molecules bring the appropriate amino acids to the ribosome, where they are joined together by peptide bonds, forming a polypeptide chain. The sequence of amino acids determines the protein’s structure and function.

Impact of Errors:
If RNA polymerase does not work during transcription, the mRNA will not be produced correctly, leading to a failure in carrying the genetic information from DNA to the ribosome. This would halt protein production entirely, affecting the cell’s function.

In translation, if tRNA does not function properly (for example, if it can’t bring the correct amino acids to the ribosome), the resulting protein will be incorrect or incomplete. This can lead to a nonfunctional protein, which may disrupt the cell’s operations and cause diseases or dysfunctions.

Question 7

Practice question:

You are walking in the woods when you encounter a bear. Explain, step-by-step, how your body would respond to this stressful situation, including the role of each gland and hormone involved, and how these hormones would help bring your body back to a normal state.

This question is an example to what COULD be on the exam (not exact)

Answer 7

When you encounter a stressful situation, like seeing a bear in the woods, your body initiates a short-term stress response to help you react quickly. The hypothalamus in your brain detects the threat and releases corticotropin-releasing hormone (CRH), signaling the adrenal medulla to secrete epinephrine (adrenaline) and norepinephrine (noradrenaline) into the bloodstream. Epinephrine causes several effects: it breaks down glycogen into glucose, increasing blood sugar and providing quick energy for muscle activity; it raises heart and respiratory rates to ensure more oxygen is delivered to muscles; and it causes blood vessels to dilate in muscles, improving blood flow. Additionally, epinephrine dilates your pupils, enhancing vision for better perception of the environment. Meanwhile, norepinephrine increases blood pressure, ensuring that oxygen and nutrients reach vital organs quickly. It also activates the amygdala, a brain region that heightens your focus and emotional response to the threat. Once the danger is gone, the parasympathetic nervous system helps return your body to a resting state by lowering heart rate, reducing blood pressure, and restoring normal glucose levels. This coordinated hormonal response prepares you to either fight or flee, ensuring your body can handle the immediate stress.

Question 8

Practice question:

At which point(s) in the nephron does reabsorption occur?
a) Proximal convoluted tubule
b) Distal convoluted tubule
c) All of the above

This question is an example to what COULD be on the exam (not exact)

Answer 8

c) all of the above
Reabsorption occurs at both the proximal convoluted tubule (PCT) and distal convoluted tubule (DCT) of the nephron. The PCT is where the majority of reabsorption occurs, including water, ions, glucose, and amino acids. The DCT also plays a role in reabsorbing ions and adjusting the composition of the filtrate based on the body’s needs.