Question

question 1
which of the following is a protein substance with no dna or rna and is thought to be the cause of mad cow disease?
○ virus
○ bacteria
○ prion
○ protozoan

question 2
1 pts
negative - feedback mechanisms:
○ minimize changes in blood glucose levels.
○ maintain homeostasis.
○ are responsible for an increased rate of sweating when air temperature is higher than body temperature.
○ all of the above are correct.

question 3
1 pts
if the secretion of oxytocin during childbirth operated as a negative - feedback control loop, what effect would it have on uterine contractions?
○ oxytocin would stimulate stronger uterine contractions.
○ oxytocin would inhibit uterine contractions.
○ there would be no changes in the strength of the uterine contractions.
○ uterine contractions would initially be weak and then gain strength after the release of the hormone.

Explanation:

Question 1

• Viruses have DNA or RNA.
• Bacteria are prokaryotes with DNA.
• Protozoans are eukaryotes with DNA.
• Prions are misfolded proteins with no nucleic acid (DNA/RNA) and are linked to mad cow disease (bovine spongiform encephalopathy).

• Negative - feedback mechanisms act to reverse changes and maintain stability (homeostasis).
• For blood glucose, negative feedback (e.g., insulin and glucagon) minimizes changes.
• Sweating when air temp > body temp is part of negative feedback to cool the body and maintain homeostasis. So all statements are correct.

• In a negative - feedback loop, the response opposes the initial stimulus.
• Oxytocin normally stimulates uterine contractions in childbirth (positive feedback). If it were a negative - feedback loop, oxytocin would inhibit uterine contractions to reverse the contraction stimulus.

Answer:

C. Prion

Question 2