Problem 1 - Campbell Biology

Question

Knowledge/Comprehension 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

Option (C): They are expressed in most individuals in a population.

Step 1 - Analyze each option

First, evaluate each given option to determine whether it correctly describes innate behaviors.

Step 2 - Option A

Innate behaviors are typically strongly influenced by genes, not weakly. Therefore, Option (A) is incorrect.

Step 3 - Option B

Innate behaviors often require specific environmental stimuli to be triggered. Therefore, Option (B) is incorrect.

Step 4 - Option C

Innate behaviors tend to be seen in most individuals of a population as they are genetic and not learned. Thus, Option (C) seems correct.

Step 5 - Option D

Innate behaviors are found across a wide range of species, including mammals. Hence, Option (D) is incorrect.

Step 6 - Determine the correct answer

Based on the analysis, the correct answer is Option (C): Innate behaviors are expressed in most individuals in a population.

Key Concepts

Genetic Influence on Innate Behaviors

Innate behaviors are actions or reactions that organisms perform naturally, without needing to learn them. These behaviors are deeply embedded in their genetics. Let's break it down:
Genes are bundles of genetic information inherited from an organism's parents. They hold codes responsible for various traits, including behaviors. When we talk about the genetic influence on innate behaviors, it means these behaviors are hardwired and passed down from generation to generation.
For instance, a spider spinning a web doesn't learn this from other spiders. It just knows. This is due to genetic coding involving numerous genes working together. Similarly, sea turtles hatch and instinctively move towards the ocean. Such behaviors are not learned, highlighting the powerful influence of genetics.

Population Expression of Innate Behaviors

Innate behaviors are not just seen in a few individuals but are generally expressed across the entire population of a species. This widespread display highlights their genetic nature.
Here's how it works:

• Innate behaviors typically emerge in every individual of the species.
• This uniformity means if you observe these behaviors in one member, you will likely see them in others too.

An example of this is the migratory patterns of birds. Almost all members of a migratory bird species will travel the same routes during migration. These behaviors are uniform and predictable because they are encoded in the birds' genetic makeup.
This consistency ensures the survival of the species, allowing individuals to perform essential actions without the need for learning or practice. Therefore, when we say that innate behaviors are expressed in most individuals in a population, we refer to this broad, uniform presence across the species.

Environmental Stimuli and Innate Behaviors

While innate behaviors are genetically driven, they often need environmental stimuli to be triggered. The interaction between genetics and the environment plays a crucial role in the expression of these behaviors.

• Environmental stimuli can be anything from changes in temperature to the presence of specific objects or other organisms.
• These stimuli act as signals that tell the organism when to exhibit certain innate behaviors.

For example, the knee-jerk reflex in humans happens in response to a specific tap on the tendon. Similarly, certain fish engage in mating dances only when the water conditions are just right. Although these actions are pre-programmed in their genes, they still rely on particular environmental triggers to occur.
Understanding the role of environmental stimuli helps us see why not all innate behaviors are constantly on display. The stimuli need to be present for these genetic instructions to be carried out.