Question

32 multiple choice 10 points
intercalated discs are a major feature of ...
○ sponge attachments to their substrate
○ white blood cells
○ cardiac muscle
○ the skin

33 multiple choice 10 points
which one of the following situations is an example of positive feedback?
○ an increase in blood pressure causes the midbrain to slow down the heartbeat
○ a decrease in blood pressure due to dehydration causes your kidneys to retain more water and release less water in urine so as to raise the blood pressure or at least keep it from dropping further.
○ the internal pressure of a fetuss head against a pregnant mothers internal wall of the cervix causes the contraction of her uterus to increase and push the baby harder against the internal wall of the cervix.
○ none of the above

Explanation:

Question 32

Intercalated discs are specialized structures that connect cardiac muscle cells, allowing for synchronized contraction. Sponges don't have such discs, white blood cells are part of the immune system and lack intercalated discs, and the skin has different cell junctions. So the correct option is the one related to cardiac muscle.

Positive feedback amplifies a change. In the fetus - cervix example, the pressure from the fetus's head increases uterine contractions, which further increase the pressure, amplifying the process. The first two options are negative feedback (they work to reverse a change, like lowering heart rate with high blood pressure or raising blood pressure with low blood pressure by retaining water).

Answer:

C. Cardiac muscle

Question 33