Problem 1 - Campbell Biology

Question

Which of the following is true of innate behaviors? (A) Their expression is only weakly influenced by genes. (B) They occur with or without environmental stimuli. (C) They are expressed in most individuals in a population. (D) They occur in invertebrates and some vertebrates but not mammals.

Step-by-Step Solution

Answer

C) They are expressed in most individuals in a population.

Step 1: Understanding Innate Behaviors

Innate behaviors are instinctual and typically performed correctly by individuals without prior experience or training. These behaviors are hardwired in the organism’s nervous system.

Step 2: Analyzing Option A

Option A states that the expression of innate behaviors is only weakly influenced by genes. This is incorrect because innate behaviors are largely determined by genetic factors.

Step 3: Analyzing Option B

Option B claims that innate behaviors occur with or without environmental stimuli. This is also incorrect, as some innate behaviors may be triggered by specific environmental cues.

Step 4: Analyzing Option C

Option C states that innate behaviors are expressed in most individuals in a population. This is correct, as these behaviors are genetically programmed and thus commonly observed within a species.

Step 5: Analyzing Option D

Option D suggests that innate behaviors occur in invertebrates and some vertebrates but not mammals. This is incorrect because innate behaviors are found across various species, including mammals.

Step 6: Conclusion

Based on the analysis of all options, the correct statement about innate behaviors is that they are expressed in most individuals in a population.

Key Concepts

Genetic Influence

Innate behaviors are deeply rooted in an organism’s genetic makeup. These behaviors are instinctive actions that occur naturally without the need for learning or practice. The genetic code an organism inherits has built-in instructions for these behaviors.
Examples of innate behaviors include a spider spinning a web and a baby grasping a finger.
The strong genetic component means:

• Most individuals of the same species will perform these behaviors similarly.
• The behaviors are stable and not influenced easily by external changes.

Understanding that genetics play a significant role helps us see why these behaviors are consistent across generations and populations.

Environmental Stimuli

While innate behaviors are primarily dictated by genetics, they can still be triggered or influenced by environmental stimuli. For example, a baby’s sucking reflex is an innate behavior that is enhanced when they feel something touching the roof of their mouth.
Some points to remember:

• Environmental cues can act as triggers for innate behaviors.
• The presence of certain stimuli can enhance or modify the expression of these behaviors.

Although the behavior itself doesn't need to be taught, the environment can play a crucial role in when and how it is displayed.

Population Expression

Innate behaviors are commonly observed within a population due to their genetic basis. This means most members of a species exhibit the same innate behaviors as part of their regular activities.
Such behaviors are:

• Universal within a species, leading to a predictable pattern of actions.
• Critical for survival and reproduction, explaining why they persist across generations.

For instance, migration in birds is an innate behavior that ensures species survival through seasonal changes. Because these behaviors are so closely tied to genetics, they are consistent among individuals, making them easy to identify and study within a population.