Science Grade 7: Natural Selection

Question 1

What is the growth rate of a population?

Answer 1

growth rate = (birth rate + immigration rate) - (death rate + emigration rate)

Question 2

What is an altricial organism?

Answer 2

Altricial organisms are helplesss at birth, and their parents give them lots of care. Example: Bird Species

Question 3

What is a precocial organism?

Answer 3

Precocial organisms can take care of themselves at birth and do not requre help from their parents. Example: Geese

Question 4

What affects population growth?

Answer 4

• Births
• Deaths
• Migration: Immigration and emigration

Question 5

What is population dispersion?

Answer 5

Population dispersion is how individuals are spread accross an environment. Some species may be clumped, clustered, evenly spaced, or randomly spaced within an area

Question 6

What is a species?

Answer 6

A species is a group of individuals that are genetically related and can breed to produce fertile young.

Question 7

What is an ecosystem?

Answer 7

An ecosystem is all the living things in an area interacting with all the abiotic parts of the environment.

Question 8

What is a population?

Answer 8

A population is a group of organisms belonging to the same species that live in the same area and react with one another

Question 9

What is a community?

Answer 9

A community is all the populations of different species that live in the same area and react with one another.

Question 10

What are the simple steps of Natural Selection?

Answer 10

1. Some kind of variation in an organisms DNA that changes a feature or trait of the organism
2. The trait or feature either gives the organism an advantage or disadvantage in it’s environment, affecting it’s death rate. The species with the advantage usually have a longer lifespan, meaning that they can reproduce more and thereby create new organisms that have the advantage-giving trait

Question 11

What is a phenotype?

Answer 11

The traits or characteristics of an individual.

Question 12

What is a genotype?

Answer 12

The genetic makeup of an individual.

Question 13

Does natural selection act on the genotype or phenotype?

Answer 13

Natural selection acts on the phenotype of an individual, not on the underlying genotype.

Question 14

What is a vestigial structure?

Answer 14

Vestigial structures, or structures that have lost their use through evolution, are important evidence of evolution. Example: an ostrich’s wings (ostriches can’t fly [anymore])

Question 15

What is an embryo?

Answer 15

An embryo is the earliest form of a species.

Question 16

What is an inherited trait?

Answer 16

Inherited traits are features that are passed from one generation to the next.

Question 17

What is an aquired trait?

Answer 17

Aquired traits are traits that are developed during a lifetime.

Question 18

What is the definition of natural selection?

Answer 18

Natural selection is the process by which organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers.

Question 19

What is an adaptation?

Answer 19

Adaptations are variations of a common trait or feature.

Question 20

What is the main thing needed for natural selection to take place?

Answer 20

Natural selection occurs when there is some variation in the inherited traits, some of these traits will give individuals an advantage over others, and the individuals with certain traits will be more likely to have more offspring.

Question 21

How is variation created in DNA?

Answer 21

When DNA is copied, errors by the enzymes are often made, adding extra or leaving away bases in a DNA strand. This creates variations in the genes, meaning that there will be variation in the species.

Question 22

What are common mutations in DNA?

Answer 22

• An additional or changed body part
• A differently colored body part
• A talent/ability

Question 23

How is variation and natural selection related?

Answer 23

Variation comes by chance, just like which trait of the organism is varied. Natural selection is what decides whether this trait will live on and succeed, and which ones will not.

Question 24

What is biotic?

Answer 24

Biotic means a living thing

Question 25

What is abiotic?

Answer 25

Abiotic means a non-living thing

Question 26

What is intraspecific competition?

Answer 26

Intraspecific competition is when organisms of the same species strive for limited resources.

Question 27

What is interspecific competition?

Answer 27

Interspecific competition is when organisms of different species strive for limited resources.

Question 28

What has to be true about available resources for competition to exist?

Answer 28

Competition exists when there are limited resources.

Question 29

What is predation?

Answer 29

Predation happens when a predator organism feeds on another living organism, or organisms known as prey.

Question 30

What is grazing?

Answer 30

In grazing, the predator eats part of the prey, but doesn’t usually kill it. An example of grazing is when cows eat grass, which grows back.

Question 31

What is true predation?

Answer 31

True predation is when a predator kills and eats it’s prey.

Question 32

What is a keystone species?

Answer 32

Predators can be a keystone species, a species that can have a large effect on the balance of organisms in an ecosystem.

Question 33

What is symbiosis?

Answer 33

Symbiosis describes a close and long-term interaction between different species. At least one species will benefit in a symbiotic relationship.

Question 34

What is mutalism?

Answer 34

Mutalism is a symbiotic relationship in which both species benefit.

Question 35

What is commensalism?

Answer 35

Commensalism is a symibotic relationship in which one species benefits while the other is not affected.

Question 36

What is a parasitism?

Answer 36

In parasitism, the parasitic species benefits, while the host species is harmed.

Question 37

Definition of ecosystem:

Answer 37

An ecosystem consists of all the living things and non-living things interacting in the same area.