Practice questions for the second midterm

The second midterm will examine material covered from lecture 15 on Friday, October 14, up to the end of lecture 25 on Monday, November 7.

The practice questions below are from Moyes and Schulte (answers and distribution of points are by me). The number of points that a question is worth will give you an indication of how much detail is required. Note that the number of points in my sample answers are often more than the question is worth, i.e., you would not have to get every point in my answer in order to get full marks.

At the end of each chapter in Moyes and Schulte, there are “Review questions”, “Synthesis questions” and “Quantitative questions”. The midterms and final will be like the “Review questions” and “Synthesis questions”, with NO questions that require a calculator. Some of the “Review questions” may be in fill-in-the-blank format.

The questions below are from the textbook chapters covering Sensory systems, Nervous systems, Muscles, and Circulatory systems.

The midterm questions will not be from Moyes and Schulte.

I will not give you feedback on your practice answers. Please compare answers with colleagues in the course.

Example of review questions

Chapter 6, Moyes and Schulte, 2^nd edition

9. Using the vertebrate ear as an example, outline some of the ways in which sensory systems amplify environmental stimuli.

10. Outer hair cells respond to sounds, but they do not make synaptic connections with afferent neurons that carry sound information to the brain. What is their role in hearing?

11. Compare and contrast the rods and cones of mammals. Does this distinction apply to all vertebrates?

Chapter 7, Moyes and Schulte, 2^nd edition

3. Outline some of the ways in which the vertebrate brain can be subdivided.

4. Compare and contrast the somatic and autonomic nervous system.

5. Would you expect the sympathetic or parasympathetic nervous system to be more active when you are (a) sitting quietly; (b) studying for an exam, (c) writing an exam?

6. Why is the autonomic nervous system sometimes termed the involuntary nervous system?

7. What is the importance of the phenomenon of basal tone in the autonomic nervous system?

8. Compare and contrast a neuron with a nerve.

Chapter 5, Moyes and Schulte, 2^nd edition

7. Discuss the role of Ca²⁺-binding proteins in muscle contraction.

Chapter 8, Moyes and Schulte, 2^nd edition

2. Trace the movement of a drop of blood through the human circulatory system, listing all of the structures it passes (including all of the parts of the heart).

4. What is the significance of the difference in pressure developed by the right and left atria of a mammalian heart.

6. Why is the lengthy refractory period of a contractile cardiomyocyte important for the function of the mammalian heart?

Note: although Moyes and Schulte’s questions don’t ask much about the molecular mechanisms through which the nervous systems affect the heart, you should still know this.

Synthesis questions with answers

Chapter 6, Moyes and Schulte, 2^nd edition

6. Peripheral vision is the ability to detect objects outside the center of the visual field. Vertebrates vary in the extent of their peripheral vision. What differences would you expect in the retina of an animal with excellent peripheral vision, compared to one with poor peripheral vision?

• Peripheral vision is achieved with photo receptor cells around the edge of the retina. These photoreceptor cells generally show convergence, i.e., multiple photoreceptor cells form synapses with a single afferent neuron.
• In an animal with excellent peripheral vision, the photoreceptor cells would show less convergence, i.e., only one or a few photoreceptor cells would form synapses with a single afferent neuron, compared with an animal with poor peripheral vision where many photoreceptor cells at the edge of the retina would form synapses with a single afferent neuron. In other words, the receptive fields would be smaller in the animal with excellent peripheral vision, even at the edges of the retina. This would improve resolution.
• In vertebrate receptor cells, photoreceptor cells are oriented towards the back of the retina, i.e., away from the incoming light. As a result, the afferent neurons are located on top of the photoreceptor cells, and so must cross through the retina to get to the brain. The region where they cross is called the optic disk, which is a blind spot in the peripheral vision.
• If the photoreceptor cells were oriented the opposite way (i.e., towards the incoming light), the afferent neurons would not have to cross through the retina, and so there would be no blind spot and so peripheral vision would be improved.
• You could also talk about the relative numbers of rods and cones around the edge of the retina, but you would have to make it clear that this would affect the relative quality of night vs. day vision.

Each bullet point would be worth one mark. This question would be worth two or three marks, i.e., you would not have to get every point to get full marks.

To me, this type of question is the type that most people find difficult, i.e., it would be a good idea to think about how to answer this type of question.

Chapter 7, Moyes and Schulte, 2^nd edition

3. Nicotinic acetylcholine receptors are found on muscle cells, and on postganglionic neurons in the sympathetic nervous system (among other places in the body). Use this information to explain why chewing nicotine-containing gum can cause a rapid heart rate and tremors in the hands of nonsmokers. (3 points)

• Chewing nicotine containing gum would result in the uptake of nicotine, which acts as an agonist to nicotinic acetylcholine receptors, i.e., it causes the same signal transduction as the natural ligand, acetylcholine.
• Stimulating nicotinic receptors on muscle cells would cause muscle contraction, e.g., tremors in hands.
• Stimulating nicotinic receptors in the postganglionic neurons of the sympathetic nervous system would mimic stimulation of the sympathetic nervous system, which is involved in the fight or flight response, and so would increase heart rate.

4. Would the autonomic nervous system function if the preganglionic neurotransmitters were different between the sympathetic and parasympathetic nervous systems, and the postganglionic neurotransmitters were the same? (3 points)

• In many cases, the sympathetic and parasympathetic nervous systems innervate the same organs but have opposite effects (e.g., sympathetic nervous system increases heart rate whereas parasympathetic nervous system reduces heart rate).
• If both nervous systems released the same neurotransmitter at the target tissue, then the system would not work because both nervous systems would cause the same effect at the target tissue.

However, it could work if

• the synapses from the two nervous systems were sufficiently separate, e.g., so that neurotransmitter from the sympathetic nervous system could not activate receptors in the parasympathetic synapses and vice versa. AND
• The synapses from the two nervous systems used different neurotransmitter receptors, e.g., so that the receptors in the sympathetic nervous system had excitatory effects and the receptors in the parasympathetic nervous system had inhibitory effects or vice versa.

Chapter 5, Moyes and Schulte, 2^nd edition

1. What genomic and genetic events might have contributed to the expansion of the myosin II family in vertebrates?

• Myosin II is also known as muscle myosin because it is the main myosin involved in contraction in muscles.
• The expansion of the myosin II family occurred through repeated gene duplications.
• When a gene is duplicated, one version can continue to perform the original function of the gene, but the other one is more "free" to evolve (less selection against it) and so can potentially gain a new/different function.
• Increased body size may have selected for more complex muscle types, and so selected for evolution of myosin genes following duplication.
• Transition from aquatic habitat to land may have selected for more complex muscle types, and so selected for evolution of myosin genes following duplication.

A question like this would be worth 3 marks, i.e., you would not have to get every point above in order to get full marks. 

Chapter 8, Moyes and Schulte, 2^nd edition

5. What would happen if the connection between the AV node and the bundle of His were blocked (in a way that didn’t directly affect any other parts of the heart)?

• Pacemaker cells of the heart are located in the sinoatrial node, and their signal is transmitted from the SA node to the AV node via the internodal pathways.
• The AV node transmits electrical signals from the internodal pathways to the bundle of His in the ventricles.
• If this connection was blocked, the coordination between the contractions of the atria and contractions of the ventricles would be blocked.
• All cardiomyocytes have an intrinsic rhythm
• Therefore, the ventricle would continue to contract, but at it's own pace, i.e., not coordinated with contractions of atria.

A question like this would be worth 4 marks, i.e., you would not have to get every point above in order to get full marks. 

Synthesis questions without answers

Chapter 6, Moyes and Schulte, 2^nd edition

1. Mechanoreceptors do not depolarize in response to light, no matter how intense the stimulus, but the eye responds to a mechanical stimulus (such as pressing on the eyeball) if the stimulus is sufficiently large. Why might this be?

7. Humans have only three types of cone photoreceptors, but can distinguish thousands of colours. How is this possible?

Chapter 7, Moyes and Schulte, 2^nd edition

1. You can surgically remove large parts of the forebrain from a mammal, and the mammal will survive. However, destruction of even relatively small parts of the hindbrain usually causes death. Why might this be so?

2. What is the functional significance of the highly folded and grooved appearance of the surface of the brain in some mammals?

5. Compare the role of presynaptic and postsynaptic mechanisms in habituation and sensitization.

Chapter 5, Moyes and Schulte, 2^nd edition

3. Describe the molecular processes of neuromuscular excitation, from the sites of neurotransmitter synthesis to Ca²⁺release within the muscle.

4. Hummingbird hearts beat at about 30 Hz (30 beats per second). Predict what you would find if you examined the structure of a hummingbird cardiomyocyte.

Chapter 8, Moyes and Schulte, 2^nd edition

1. What are some possible advantages of a double circulation over a single-circuit circulation?

2. Explain the changes in blood pressure as blood flows through the mammalian circulatory system.

3. Aortic blood flow starts to increase only some time after the initiation of ventricular contraction. Similarly, aortic blood flow continues at a relatively high level well into the diastolic period. Explain why.

6. During an experiment dogs were given the drug atropine, which abolishes parasympathetic nerve transmission. What effects would you expect on the heart and why?