Biology unit 2

What is natural selection?

Refers to a process that describes organisms, better suited to their enviroment, due to having favourable alleles, will be able to have more chance at surviving and reproducing.

What are the 5 steps in Natural Selection?

Variation, selection pressures, survival advantage, survival of the fittest/reproductive advantage, change in allele frequency.

What is variation?

Genetic variations that alter gene activity, can introduce different traits in an organism. If a trait is advantageous and helps the individual survive and reproduce

What are selection pressures?

Selection pressures are external agents which affect an population’s ability to survive or reproduce in a given environment. Ie. Predation, temperature, food availability, disease, environmental conditions.

Survival of the fittest

The organisms that are better suited to their environment and survive the pressure of selective agents.

Survival advantage

Any factor in an organism's development that gives it a benefit or advantage that makes survival and reproduction possible.

What is embryology?

The study of the formation and development of embryo and fetus. When comparing: gill slits, tail, forelimb bud, notochord. Can provide evidence for evolution and in the early stage they look similar, which means there were common ancestors.

sources of gene variation?

mutation - permanent change in DNA, independent assortment - chromosomes align randomly occurs in meiosis, random fertilisation - chance that any sperm can fertilise any egg.

What are vestigial organs?

Organs that were reduced in size throughout evolution since they were no longer functional in the way they were in their ancestral form. These remnants can provide evidence for evolution as a specific once-larger sized body part would’ve been used by a common ancestor. For example, the appendix (humans used to herbivores, so it was used for digestion)

What does a change in Allele frequency mean?

A process that continuously selects for or against traits in a population, although favourable ones increase in frequency

What does isolation mean i?

Geological, ecological, and reproduction barriers that prevent the allele flow of a species, causing interbreeding unsuccessful.

What is speciation?

Process by which one species split into two or more separate species.

How does speciation occur?

Variation. Isolation. Selection pressures, survival of fittest. accumulation. Time. Speciation occurs through isolation (interbreeding not possible,, specie separates from population), then selection pressure may cause mutations in order for the specie to survive. And when the genetic difference grows throughout the population as mutations and selection for different traits will start to accumulate, this specie will be considered different.

How do fossils provide evidence for evolution?

You are able to see the fossil history which shoes how the life form evolved into more complex forms.

How do you know if an animal is in the species?

They can reproduce fertile offspring in natural conditions successfully.

Difference between homologues structures and analogous structures?

Homologous structures have the same structure. ie. Pentadactyl limb in bats, humans and whales.

Analogous structures have the same function, but do not come from a common ancestor. ie. wings on an insects, birds and bats.

What is biodiversity?

Refers to the variety of all living things how they interact with each other.

Evolution Meaning

Refers to the change in allele frequency of a population over several generations

What does evolution result in?

Results in the change in allele frequency over generations

What are the three types of evidence you use?

Biochemistry (DNA), Anatomy, and fossils.

What are the traits in hominins?

Increase in carnal capacity (brain), greater rounded skull, flatter foreheads, smaller teeth, reduction in prognathism (less protrusion of jaw). centralised forearm magnum for balance

What is evolution?

The change in allele frequency in a population over generations, due to selection pressures.

Order of events for speciation

isolation, natural selection, random mutation and time

Types of comparative Anatomy

Embryology, Vestigial organs, Homologues structures.

What are fossils?

Preserved remains of ancient organisms preserved in rocks.

what are hominins?

Humans and bipedal ancestors

What is a species?

A group of organisms that can breed to produce fertile offspring in natural conditions

A new species can form in one generation. True or false?

false

Can a population evolve over a generation?

No, take several