SCIENCE 7B LESSON 2 Flashcards
stimulus
is anything that causes a reaction or change in an organism. A stimulus can be an environmental factor such as temperature.
response
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.
behavior
A set of actions taken by an organism in response to a stimulus is called a behavior.
homeostasis
is maintaining a stable balance in the body. Organisms’ bodies constantly respond to stimuli to maintain homeostasis.
hormone
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.
taxis
is the movement of organisms toward or away from an external stimulus. An organism shows positive taxis when it moves toward a stimulus.
tropism
the movement of a plant in response to an external stimulus, such as light or gravity.
hibernation
A deep sleep during which an animal slows down its body processes to save energy
estivation
When internal processes slow down during hot, dry weather
species
is a group of organisms that can reproduce only with one another and not with other organisms. For example, mockingbirds reproduce with other mockingbirds.
population
is a group of organisms of the same species that live in the same place at the same time
variation
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
evolution
refers to the process by which
populations gradually change over time
artificial selection
The practice by which humans breed specific plants or animals for desired traits is called selective breeding,
natural selection
is the process by which organisms that inherit helpful traits tend to reproduce more successfully than other organisms do.
What are the 4 parts that contribute to the process of evolution by natural selection?
overproduction, genetic variation, selection, and adaptation
overproduction
More offspring are usually born than the environment can support.
Selection
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
adaptation
An inherited trait that improves the survival and reproductive success of an organism
Genetic variation
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
habitat
The specific place where an organism lives is
biodiversity
The number and variety of plants, animals, and other organisms living in a area
taxonomy
is the science of naming and classifying organisms.
classification
The organization of living things into groups based on their traits
sustainability
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
dichotomous key
They are often used for field guides to identify specimens such as plants and animals.
