Science Grade 7: Natural Selection Flashcards
What is the growth rate of a population?
growth rate = (birth rate + immigration rate) - (death rate + emigration rate)
What is an altricial organism?
Altricial organisms are helplesss at birth, and their parents give them lots of care. Example: Bird Species
What is a precocial organism?
Precocial organisms can take care of themselves at birth and do not requre help from their parents. Example: Geese
What affects population growth?
- Births
- Deaths
- Migration: Immigration and emigration
What is population dispersion?
Population dispersion is how individuals are spread accross an environment. Some species may be clumped, clustered, evenly spaced, or randomly spaced within an area
What is a species?
A species is a group of individuals that are genetically related and can breed to produce fertile young.
What is an ecosystem?
An ecosystem is all the living things in an area interacting with all the abiotic parts of the environment.
What is a population?
A population is a group of organisms belonging to the same species that live in the same area and react with one another
What is a community?
A community is all the populations of different species that live in the same area and react with one another.
What are the simple steps of Natural Selection?
- Some kind of variation in an organisms DNA that changes a feature or trait of the organism
- 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
What is a phenotype?
The traits or characteristics of an individual.
What is a genotype?
The genetic makeup of an individual.
Does natural selection act on the genotype or phenotype?
Natural selection acts on the phenotype of an individual, not on the underlying genotype.
What is a vestigial structure?
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])
What is an embryo?
An embryo is the earliest form of a species.
What is an inherited trait?
Inherited traits are features that are passed from one generation to the next.
What is an aquired trait?
Aquired traits are traits that are developed during a lifetime.
What is the definition of natural selection?
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.
What is an adaptation?
Adaptations are variations of a common trait or feature.
What is the main thing needed for natural selection to take place?
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.
How is variation created in DNA?
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.
What are common mutations in DNA?
- An additional or changed body part
- A differently colored body part
- A talent/ability
How is variation and natural selection related?
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.
What is biotic?
Biotic means a living thing
What is abiotic?
Abiotic means a non-living thing
What is intraspecific competition?
Intraspecific competition is when organisms of the same species strive for limited resources.
What is interspecific competition?
Interspecific competition is when organisms of different species strive for limited resources.
What has to be true about available resources for competition to exist?
Competition exists when there are limited resources.
What is predation?
Predation happens when a predator organism feeds on another living organism, or organisms known as prey.
What is grazing?
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.
What is true predation?
True predation is when a predator kills and eats it’s prey.
What is a keystone species?
Predators can be a keystone species, a species that can have a large effect on the balance of organisms in an ecosystem.
What is symbiosis?
Symbiosis describes a close and long-term interaction between different species. At least one species will benefit in a symbiotic relationship.
What is mutalism?
Mutalism is a symbiotic relationship in which both species benefit.
What is commensalism?
Commensalism is a symibotic relationship in which one species benefits while the other is not affected.
What is a parasitism?
In parasitism, the parasitic species benefits, while the host species is harmed.
Definition of ecosystem:
An ecosystem consists of all the living things and non-living things interacting in the same area.
