BioNB 2220 Quiz 01 Cornell University Feb. 5-10, 2016

QUIZ 01 Instructions: Download the quiz from Blackboard (in Quiz Questions Folder), print a copy and use the paper copy to work through the various questions and problems. Mark the correct answers on it. When you are ready to submit your answers, you will see the quiz posted under Quiz Answer Sheets. Click the quiz name to launch the quiz. Enter your answers to each of the corresponding numbered questions onto the blank answer sheet (the questions will not be repeated, simply a blank page for your answers). The quiz may be saved if you do not finish entering your answers in one sitting. When you are finished with the quiz, make sure to submit your answers and they will be recorded. For each question, select the one best answer from among those given (multiple choice). Each question is worth one (1) point. Please note that there will generally be short answer "thought questions" at the end of each quiz. These will not be graded and are worth zero point towards your quiz grade. However they are good examples of the types of short answer questions that will be on exams. Therefore, we encourage you to attempt these questions and compare your answers to those on the answer key.

1. Below is one of Cajals drawings of the neural circuitry of the retina. Which of the numbered arrows indicate axons, according to our class discussion?

a) All of them b) 1, 2, 3 c) 2 & 4 d) 1 & 2 e) 3 & 4

BioNB 2220 Quiz 01 Cornell University Feb. 5-10, 2016 2. A man in his 40s has a stroke that affects one of the brain regions labeled a-e in the drawing

above. After the stroke, he is unable to see objects on his right side. Which brain area was most likely affected by the stroke?

Answer: a, b, c, d, e. 3. In the in class exercise, we showed cerebellar Purkinje neurons and cerebellar Granule cells (see

below) and asked you to determine what their function was. Although this was difficult, you can conclude some functionality of these cells from their anatomy. Which of the following could you logically conclude about the similarities/differences between these two types of neurons based only on their anatomical structure?

a) Purkinje cells are larger, and thus are more involved with cerebellar processing than are Granule cells.

b) Both Purkinje cells and Granule cells are involved in motor control. c) Purkinje cells are larger, and thus transmit more important information to other neurons than

Granule cells. d) Due to more dendritic branching, Purkinje cells have a higher probability of having synaptic

inputs from more cells than Granule cells. e) More than one of the above can be reasonably concluded.

BioNB 2220 Quiz 01 Cornell University Feb. 5-10, 2016 4. Which of the following approaches could you use to demonstrate the existence of the map of

visual space in Primary Visual Cortex (V1)?

a) Recording the electrical responses of many neurons in the occipital cortex to visual stimuli presented in different locations in space.

b) Depositing sufficient synapse-crossing tracer to fill every retinal cell in both eyes. c) Electrically stimulating small regions of occipital cortex in awake patients and determining

where in their visual field they experience spots of light. d) All of the above e) Only a) and c)

5. Following a motor bike accident, a 22-year old man shows signs of paraplegia (complete

paralysis and loss of feeling in lower body, but not the arms). Name (i) the site of injury and (ii) the type of lesion.

a) Sacral pinal cord, bilateral. b) Sacral spinal cord, unilateral. c) Thoracic spinal cord, bilateral. d) Thoracic spinal cord, unilateral.

6. A typical neuron has a resting potential of zero millivolts. The membrane is permeable to

sodium, potassium and chloride and no other ions. Which of the following situations is NOT one where the membrane could achieve a zero millivolt resting potential?

a) Sodium higher outside than inside, Potassium higher outside than inside, Chloride higher

outside than inside. b) Potassium higher inside than outside, Sodium higher inside than outside, Chloride higher

inside than outside. c) Sodium higher inside than outside, Chloride higher inside than outside, Potassium higher

outside than inside. d) Sodium higher inside, Chloride higher outside, Potassium higher inside.

BioNB 2220 Quiz 01 Cornell University Feb. 5-10, 2016 7. The solutions in chambers a and b below contain only KCl dissolved in water, but at unknown

concentrations. The membrane potential (Va) across the membrane separating the two compartments is stable at -58 mV. Your student assistant tells you that he has just added more powdered KCl to the right side of the chamber to increase the concentration of KCl on that side. You look at the potential difference and see that it is still -58mV. Which of the following must be true.

a) The membrane is not permeable to Cl-. b) The concentration of chloride on the side b is 10 times higher than that on side a after the

addition of the KCl. c) The membrane is equally permeable to both K+ and Cl-. d) Your assistant is mistaken or is lying. He did not add any KCl. e) None of the above are true.

8. A neuron has external and internal concentrations of Na+, K+, and Cl- such that the Nernst

potential for each of the ions is: Na+: -10 mV K+: -80mV Cl-: -75mV

If the membrane is equally permeable to each of the ions and we use an electrode to pass current

to hold the membrane potential at 80mV, which of the following statements is false? (Pick answer e, if both c and d are false.)

a) There is no net flow of K into or out of the neuron at80mV. b) Sodium is flowing into the neuron at80mV. c) Chloride is flowing out of the neuron at80 mV. d) The outward flow of chloride always equals the inward flow of sodium at 80mV. e) Both (c) and (d) are False.

BioNB 2220 Quiz 01 Cornell University Feb. 5-10, 2016 9. The concentration of a positively charged ion is higher outside than inside a neuron. The

permeability of the membrane to this ion is near 0 and the initial membrane potential (Vm) is 0 mV. If the permeability to this ion increases drastically, and all other variables remain the same, what will happen to the Vm of the cell?

a) Vm will become positive. b) Vm will become negative. c) Vm will remain constant. d) There is not enough information to know what will happen.

10. Thought question (ungraded): There are some examples of neurons which do not have an axon

(but do have dendrites). What do you think their role could be in a neural circuit? 11. Thought question (ungraded): Suppose all of the sodium and potassium concentrations (both

inside and outside a neuron) that were given in class were cut in half and that the relative permeability of the membrane to sodium and potassium were unchanged.

A) What would happen to the resting membrane potential of the cell in this case?

B) Is the above case similar to if there were no sodium-potassium pumps to maintain ion

gradients across neurons? Explain why or why not. 12. Thought question (ungraded): What is the advantage to the brain of having localized rather

than distributed function? For instance, why are there areas localized for particular visual information (e. g. mapping in space etc.) like primary visual cortex rather than distributing these maps across cortical regions?