SCIENCE 7B LESSON 2

Question 1

stimulus

Answer 1

is anything that causes a reaction or change in an organism. A stimulus can be an environmental factor such as temperature.

Question 2

response

Answer 2

is an organism’s reaction to a stimulus. For example, some animals respond to cold temperatures by growing extra fur to stay warm, while others respond by moving to warm environments.

Question 3

behavior

Answer 3

A set of actions taken by an organism in response to a stimulus is called a behavior.

Question 4

homeostasis

Answer 4

is maintaining a stable balance in the body. Organisms’ bodies constantly respond to stimuli to maintain homeostasis.

Question 5

hormone

Answer 5

is a chemical signal produced in one part of an organism that affects cell activity in another part of the organism. Hormones move more slowly than electrical signals.

Question 6

taxis

Answer 6

is the movement of organisms toward or away from an external stimulus. An organism shows positive taxis when it moves toward a stimulus.

Question 7

tropism

Answer 7

the movement of a plant in response to an external stimulus, such as light or gravity.

Question 8

hibernation

Answer 8

A deep sleep during which an animal slows down its body processes to save energy

Question 9

estivation

Answer 9

When internal processes slow down during hot, dry weather

Question 10

species

Answer 10

is a group of organisms that can reproduce only with one another and not with other organisms. For example, mockingbirds reproduce with other mockingbirds.

Question 11

population

Answer 11

is a group of organisms of the same species that live in the same place at the same time

Question 12

variation

Answer 12

is the differences that occur in individuals within a species. Variation of physical characteristics is partly due to the genetic variation of the individuals within a species or a population

Question 13

evolution

Answer 13

refers to the process by which
populations gradually change over time

Question 14

artificial selection

Answer 14

The practice by which humans breed specific plants or animals for desired traits is called selective breeding,

Question 15

natural selection

Answer 15

is the process by which organisms that inherit helpful traits tend to reproduce more successfully than other organisms do.

Question 16

What are the 4 parts that contribute to the process of evolution by natural selection?

Answer 16

overproduction, genetic variation, selection, and adaptation

Question 17

overproduction

Answer 17

More offspring are usually born than the environment can support.

Question 18

Selection

Answer 18

Remember that selection works only on traits that exist in a population. Individuals with a helpful trait are more likely to survive to reproduce. As a result, the trait is “selected” for becoming more common in the next generation

Question 19

adaptation

Answer 19

An inherited trait that improves the survival and reproductive success of an organism

Question 20

Genetic variation

Answer 20

Within a population, there are naturally occurring variations in traits. For example, of the two jaguars to the left, one has a larger jaw than the other. The different jaw sizes result from genetic differences. Genetic differences, or variations, pass from parents to their offspring

Question 21

habitat

Answer 21

The specific place where an organism lives is

Question 22

biodiversity

Answer 22

The number and variety of plants, animals, and other organisms living in a area

Question 23

taxonomy

Answer 23

is the science of naming and classifying organisms.

Question 24

classification

Answer 24

The organization of living things into groups based on their traits

Question 25

sustainability

Answer 25

is the ability of the environment to meet human needs indefinitely. In the past few decades, sustainability has become a concern as important resources such as fossil fuels are at risk of being used up

Question 26

dichotomous key

Answer 26

They are often used for field guides to identify specimens such as plants and animals.