Unit 1 · 15 to 25% of the exam

Unit 1 practice test: Biological Bases of Behavior

twelve questions, every option explained

12 exam-style questions from the unit, free, with an explanation for every option. Most have four answer choices, as on the real exam, and a few ask for a number you can work out by hand; sets share one study summary, data table, graph or figure. Covers: Interaction of Heredity and Environment; Overview of the Nervous System; The Neuron and Neural Firing; The Brain; Sleep; Sensation.

Start at question 1

Study

Speech after damage to one brain region

Introduction

Researchers asked whether damage to the lower part of the left frontal lobe affects producing speech more than understanding it.

Participants

Two groups of adults at one rehabilitation hospital: 10 patients who had a stroke that damaged the lower left frontal lobe (confirmed by brain scans) and 10 patients of similar age whose strokes damaged other areas. A hospital review board approved the study, and every patient (or a family member, when a patient could not sign) gave informed consent. Names were replaced with code numbers in the records.

Method

Each patient described a picture for one minute; speech was scored as the number of words spoken in that minute. Understanding was scored as the number of 20 spoken instructions ("Point to the cup") carried out correctly.

Results

Frontal-damage group: 18 words per minute and 17 of 20 instructions. Other-damage group: 92 words per minute and 18 of 20 instructions.

Invented study for practice.

Average scores by group (invented data for practice)
GroupWords per minuteInstructions correct (of 20)
Lower left frontal damage1817
Damage elsewhere9218

1. Why is this study not an experiment?

  1. The groups already existed; no one assigned the damage
  2. The patients came from a single rehabilitation hospital
  3. Speech was measured with a one-minute picture task
  4. Each patient or a family member gave informed consent
Show the answer

In an experiment the researcher manipulates the variable and randomly assigns participants. Brain damage cannot ethically be assigned, so the study compares groups that already differ.

  • Correct: The groups already existed; no one assigned the damage: Right: nothing was manipulated or randomly assigned; the damage already existed.
  • The patients came from a single rehabilitation hospital: Studying one hospital limits who the results describe, but a one-site study can still be an experiment.
  • Speech was measured with a one-minute picture task: How speech was measured is the operational definition; it does not decide the method.
  • Each patient or a family member gave informed consent: Informed consent is an ethical safeguard, used in experiments too.

2. Which conclusion do the results best support?

  1. The lower left frontal lobe matters more for producing speech than for understanding it
  2. The lower left frontal lobe matters more for understanding speech than for producing it
  3. Damage anywhere in the brain lowers speech and understanding about equally
  4. The lower left frontal lobe is the single region involved in language
Show the answer

The frontal group spoke far fewer words (18 vs 92) but followed almost as many instructions (17 vs 18): production was hit hard, understanding barely. That pattern fits Broca's area.

  • Correct: The lower left frontal lobe matters more for producing speech than for understanding it: Right: speech output dropped sharply while understanding stayed close to the other group's.
  • The lower left frontal lobe matters more for understanding speech than for producing it: This reverses the result: understanding was nearly the same in both groups.
  • Damage anywhere in the brain lowers speech and understanding about equally: The two groups differed a lot in words per minute, so the damage location mattered.
  • The lower left frontal lobe is the single region involved in language: Wernicke's area in the temporal lobe is also involved in language; the study does not show only one region matters.

3. Which ethical safeguard does the summary describe, and how was it applied?

  1. Confidentiality: names in the records were replaced with code numbers
  2. Debriefing: patients were told the true purpose after being deceived
  3. Random assignment: patients were placed in groups by chance
  4. Protection from harm: patients were given a treatment to reverse damage
Show the answer

The summary says names were replaced with code numbers, which keeps each patient's data confidential. It also describes review board approval and informed consent.

  • Correct: Confidentiality: names in the records were replaced with code numbers: Right: replacing names with codes protects confidentiality.
  • Debriefing: patients were told the true purpose after being deceived: The summary describes no deception, so there was nothing to debrief.
  • Random assignment: patients were placed in groups by chance: Random assignment is a design feature, not an ethical safeguard, and it was not used here.
  • Protection from harm: patients were given a treatment to reverse damage: No treatment was given; the summary does not describe this.

Data

Heart rate before, during and after a surprise

050100150200020406080100120Time (seconds); loud noise at 60 sHeart rate (beats per minute)

4. What change does the graph show right after the loud noise?

  1. Heart rate fell from about 110 to 70 beats per minute
  2. Heart rate stayed close to 70 beats per minute
  3. Heart rate rose slowly over the full four minutes
  4. Heart rate rose from about 70 to 110 beats per minute
Show the answer

The line jumps from about 70 to 110 just after the noise at 60 seconds.

  • Heart rate fell from about 110 to 70 beats per minute: That happens later, as the heart rate recovers.
  • Heart rate stayed close to 70 beats per minute: There is a sharp rise after the noise.
  • Heart rate rose slowly over the full four minutes: The rise is sudden, followed by a slow fall.
  • Correct: Heart rate rose from about 70 to 110 beats per minute: Right: the peak comes at 90 seconds.

5. Which division explains the fall in heart rate from 90 to 240 seconds?

  1. The parasympathetic division calming the body
  2. The sympathetic division arousing the body
  3. The somatic system relaxing the skeletal muscles
  4. The spinal cord blocking messages from the brain
Show the answer

Once the surprise passes, parasympathetic activity slows the heart back toward its resting rate.

  • Correct: The parasympathetic division calming the body: Right: heart rate returns toward rest.
  • The sympathetic division arousing the body: Sympathetic arousal raised the heart rate after the noise.
  • The somatic system relaxing the skeletal muscles: Heart rate is controlled by the autonomic system, not the somatic.
  • The spinal cord blocking messages from the brain: Nothing was blocked; the body returned toward rest.

6. About how long after the noise did the heart rate get back within a few beats of its resting level?

  1. About 30 seconds, near 90 seconds
  2. About 3 minutes, near 240 seconds
  3. About 1 minute, near 120 seconds
  4. It did not come back down during the recording
Show the answer

The noise came at 60 seconds and the heart rate was back near 72 at 240 seconds: about three minutes. Arousal is fast; calming takes longer.

  • About 30 seconds, near 90 seconds: At 90 seconds the heart rate was at its peak, 110.
  • Correct: About 3 minutes, near 240 seconds: Right: it is about 72 at 240 seconds, close to the resting 70.
  • About 1 minute, near 120 seconds: At 120 seconds it was still about 98.
  • It did not come back down during the recording: It fell to about 72 by 240 seconds.

7. Why can a trait be highly heritable and still differ between two groups for purely environmental reasons?

  1. Highly heritable traits are fixed at birth and do not change
  2. Heritability is measured with adoption studies, which ignore groups
  3. Heritability describes differences within a group, not between groups
  4. Groups differ by heredity alone, while individuals differ by environment
Show the answer

Plant the same mix of seeds in rich and poor soil. Within each field, height differences are mostly genetic; the difference between the fields is entirely the soil. Heritability within groups says nothing about the cause of differences between them.

  • Highly heritable traits are fixed at birth and do not change: Heritable traits can change with nutrition, schooling and much else.
  • Heritability is measured with adoption studies, which ignore groups: The method does not matter; the point is what heritability describes.
  • Correct: Heritability describes differences within a group, not between groups: Right: two fields of the same seeds in rich and poor soil differ because of the soil.
  • Groups differ by heredity alone, while individuals differ by environment: Neither part of this holds; both sources vary at both levels.

8. Dev steps on a tack and his foot jerks back before he feels any pain. Which pathway carried this reflex?

  1. Sensory neuron to interneuron in the spinal cord to motor neuron
  2. Motor neuron to interneuron in the spinal cord to sensory neuron
  3. Sensory neuron straight to the brain, then back to a motor neuron
  4. Interneuron in the foot to sensory neuron to motor neuron
Show the answer

In a reflex arc the sensory neuron carries the message into the spinal cord, an interneuron passes it on, and a motor neuron moves the muscle. The brain gets the message a moment later, which is when he feels the pain.

  • Correct: Sensory neuron to interneuron in the spinal cord to motor neuron: Right: sensory neuron in, interneuron in the spinal cord, motor neuron out.
  • Motor neuron to interneuron in the spinal cord to sensory neuron: This runs the arc backward: sensory neurons carry information in and motor neurons carry commands out.
  • Sensory neuron straight to the brain, then back to a motor neuron: The spinal cord handles the reflex without waiting for the brain, which is why the foot moves before the pain is felt.
  • Interneuron in the foot to sensory neuron to motor neuron: Interneurons sit in the brain and spinal cord, not in the foot.

9. As she drifts off, Priya suddenly feels as if she is falling and her leg jerks, waking her. In which stage did this most likely happen?

  1. N1
  2. N3
  3. REM
  4. N2
Show the answer

Hypnagogic sensations, such as the feeling of falling and a sudden jerk, happen in N1, the light transition from waking to sleep.

  • Correct: N1: Right: falling sensations and jerks come as you first drift off, in N1.
  • N3: N3 is deep sleep later in the cycle; people are hard to wake from it.
  • REM: In REM the major muscles are largely paralyzed, so a jerking leg is not typical.
  • N2: N2 comes after N1; the falling feeling marks the very start of sleep.

10. A singer can just notice a change of 3 hertz in a 300-hertz tone. Assuming Weber's law holds, what is the smallest change in hertz she would notice in a 900-hertz tone?

Type a number (Hz). No calculator needed: work it out by hand, as on the exam.

Show the answer

The Weber fraction is 3 / 300 = 0.01. The just-noticeable difference for 900 Hz is 0.01 × 900 = 9 Hz.

  • Answer: 9 Hz

11. A psychologist explains why people around the world find sweet, fatty foods appealing by pointing out that ancestors who sought out these rare, energy-rich foods were more likely to survive and have children. Which perspective is this?

  1. The behavioral perspective
  2. The humanistic perspective
  3. The sociocultural perspective
  4. The evolutionary perspective
Show the answer

Evolutionary psychology explains behavior and mental processes by how they helped our ancestors survive and reproduce, through natural selection.

  • The behavioral perspective: The behavioral perspective explains behavior by what a person learned from consequences in their own lifetime.
  • The humanistic perspective: The humanistic perspective stresses growth and free choice.
  • The sociocultural perspective: The sociocultural perspective looks at the influence of culture and other people.
  • Correct: The evolutionary perspective: Right: it explains a trait by its survival and reproduction advantages.

12. A car accident damages a person’s spinal cord at the middle of the back. Why might he lose feeling and movement in his legs but not in his arms?

  1. The spinal cord belongs to the peripheral nervous system, which controls the legs
  2. The injury stopped the parasympathetic division from calming the legs
  3. The legs are controlled by the autonomic system and the arms by the somatic
  4. Messages between the brain and the legs pass through the damaged part of the cord
Show the answer

The spinal cord carries messages between the brain and the body. An injury cuts off the parts of the body whose nerves connect to the cord below it.

  • The spinal cord belongs to the peripheral nervous system, which controls the legs: The spinal cord is part of the central nervous system.
  • The injury stopped the parasympathetic division from calming the legs: Losing feeling and movement is about blocked messages, not calming.
  • The legs are controlled by the autonomic system and the arms by the somatic: Both arms and legs are moved by the somatic system.
  • Correct: Messages between the brain and the legs pass through the damaged part of the cord: Right: the nerves for the arms join the cord above the injury.