Grade 11 Pre-AP Biology - Exam Review

Plato and Aristotle believed that species were _______ and _________.

perfect, permanent

Why was evolution denied at first?

because it was believed that God created all life and therefore all life must be perfect and unchanging

_________ was not considered as a possible fate for species.

extinction

Strata

layers of fossils

How did the discovery of fossils shape how people saw evolution?

• many of the fossils were from species that no longer existed, suggesting that extinction was possible

• fossils found closer to the surface were more alike to living species today

Catastrophism

sudden natural disasters wipe out old species and are then replaced by a new species

Gradualism

the Earth changes gradually over time

Uniformitarianism

the Earth changes at a uniform pace throughout time

Lamarck vs Darwin

Lamarck: suggested that species change over time to adapt to their environments, and that during the course of the individual’s lifetime, they could acquire new traits based on “felt needs.” Those traits could then be passed on to offspring (e.g. saying a giraffe stretches its neck to reach food and therefore their children will be born with long necks)

Darwin: suggested the idea of Natural Selection; only the characteristics of individuals who survive are passed onto the next generation

What was the logic behind Darwin’s Theory of Natural Selection?

• species typically produce more offspring than the environment can support + population sizes tend to remain stable = members of the same species must compete with each other for survival

• individuals within a species differ from one another in their characteristics = individuals with characteristics better adapted to their environment will have a higher chance of surviving

• the characteristics of the parents tend to be passed onto the offspring = those who survive will have the chance to reproduce and pass on their characteristics; those who don’t survive won’t

Natural Selection

“survival of the fittest” in which only those who best adapt to their environment survive and get to pass on their genes/characteristics

Carrying Capacity

populations grow exponentially until the environment cannot support their needs anymore

Descent With Modification

regarding natural selection; when only traits of surviving members of a species get passed down, then a gradual change in the overall characteristics of the species will occur

Evidence for Evolution (Anatomy)

• Homologous Features

• Analogous Features

• Vestigial Features

Homologous Features

anatomical features that evolved from the same origin (e.g. fin of a whale, wing of a bat, hand of a human)

Analogous Features

anatomical features that look similar but are NOT evolved from the same origin (e.g. sharks, penguins, whales)

Vestigial Features

anatomical features that still exist in an organism’s anatomy but have no apparent function/purpose, suggesting that it is left over from the evolutionary past (e.g. whale’s hip bone, humans’ tail bone)

Evidence for Evolution (Embryology)

during development, organisms will sometimes show vestigial features that are no longer there at birth

Evidence for Evolution (Biogeography)

it is sometimes possible to infer the evolutionary history of different species by tracking how the populations may have moved from one area to another

Evidence for Evolution (Biochemistry)

chemical reactions inside closely related species will often be similar if not identical

Evidence for Evolution (Genetics)

human and chimpanzee DNA is 98% similar, suggesting that we are close relatives and perhaps evolved from the same ancestors

Types of Selection

• Directional

• Stabilizing

• Disruptive

• Sexual

• Artificial

Directional Selection

selection against one extreme

FOR: one extreme trait

AGAINST: the other extreme

(e.g. long wiggly tails on a lizard look like a snake and scare predators. The longer the tail, the more it looks like a snake.)

Stabilizing Selection

selection against both extremes

FOR: moderate traits

AGAINST: both extremes

(e.g. short tails mess up a cat’s balance. Long tails drag on the ground.)

Disruptive Selection

selection against the mean

FOR: both extremes

AGAINST: moderate traits

(e.g. short tails on squirrels help keep predators from catching you on the ground. Long tails are good for balance in the trees.)

Sexual Selection

members of the same species compete with other males for the right to mate with a female. Therefore, species will evolve and have traits that will allow them to better attract a mate, thereby having a greater chance of reproducing

(e.g. only males have horns/antlers in many mammals, and they are used for males to fight each other for the right to mate with females)

Sexual Dimorphism

males and females of a species look different from each other (e.g. antlers vs no antlers)

Sexual Conflict

when evolutionary needs of males and females of a species are different (males are able to produce unlimited sperm, whereas females produce a limited # of eggs)

males want to mate ASAP

females want to be more selective in who they choose to reproduce with

elaborate mating rituals (e.g. fighting, dancing, singing) males are forced to perform are necessary to counteract sexual conflict

Artificial Selection

when humans are picking what individuals survive and mate; otherwise known as breeding (e.g. dogs)

Patterns of Evolution

• Divergent Evolution

• Radiation Evolution

• Parallel Evolution

• Convergent Evolution

• Co-Evolution

Divergent Evolution

population is split and evolves into two different species (exposed to different selective pressures)

Radiation Evolution

population is split multiple times and evolves into many different species with a common ancestor (exposed to several different environments)

Parallel Evolution

two species diverge from a common ancestor but end up evolving to have similar traits anyways (exposed to same environment but are two different species)

Convergent Evolution

species from greatly different evolutionary paths end up developing similar traits (to similar selective pressures, e.g. all analogous features)

Co-Evolution

when the evolution of one species directly influences the evolution of another

• Mutualism

• Predation/Paracitism

• Competition

Mutualism

win-win

Predation/Parasitism

win-lose

Competition

lose-lose

Evolutionary Arms Race

as the prey evolves to run faster, so will the predator

Genetic Drift

changes in the frequency of alleles within a population

these changes are caused by random chance, and affect the population more strongly if the population is small

(e.g. some black and red ants get run over on the sidewalk by a bike. the remaining ants may be mostly red by random chance = bottleneck effect)

Bottleneck Effect

population endures a sudden traumatic event that suddenly shrinks the population size. By random chance, the genetic makeup of the survivors may differ dramatically from that of the original population

Founder Effect

small group of individuals leaves a larger population to establish a new population elsewhere

the genetic makeup of the new population may differ significantly from the original population

Why is genetic diversity so important to evolution?

Genetic diversity is so important to evolution because without it, nothing would ever evolve. If everything reproduced asexually, all offspring would be carbon copies of the parent, which means nothing would ever change. Therefore, evolution would not be possible without genetic diversity.

Why is sexual reproduction so important to evolution (compared to asexual reproduction)?

Though sexual reproduction takes longer compared to asexual reproduction, it does have an advantage in that offspring produced by sexual reproduction have more genetic diversity, allowing them to overcome challenges in their environment with more ease.

Why do pesticides and antibiotics lose effectiveness with each use?

as bacteria are exposed over and over, they evolve to survive higher and higher concentrations each time

Mutations only affect evolution if they are __________.

inheritable

Harmful Mutations

• Decreases the individual’s ability to survive

• Lethal mutations usually do not last very long in the gene pool

• Some harmful mutations may persist in the gene pool (especially if they are recessive)

Neutral Mutations

• Has no effect on the individual’s ability to survive

Beneficial Mutations

• Improves the individual’s ability to survive

• A single new “allele” in one individual can gradually become the most frequent allele in the gene
  pool. A new allele can rapidly become the most frequent gene if the selective pressure is great.

What is the ultimate outcome of natural selection and evolution?

the creation of a new species; speciation

Microevolution

the evolution of a new species from another species

Macroevolution

the evolution of entire groups of species

At what point are populations considered 2 separate species?

when they can no longer successfully reproduce with each other

Gene Flow vs Reproductive Isolation

Gene Flow: transfer of genes between 2 populations (through reproduction)

Reproductive Isolation: species are prevented from reproducing with each other - increasing the probability of speciation

Prezygotic Mechanisms

first line of defence to prevent reproduction; to prevent formation of a zygote

Ecological Isolation

Prevention of Mating

• populations do not reproduce because they live in different areas of an ecosystem

Temporal Isolation

Prevention of Mating

• populations may live in the same area but are reproductively active at different times

Behavioural Isolation

Prevention of Mating

• populations have different mating rituals for attracting a mate

Mechanical Isolation

Prevention of Fertilization

• individuals may attempt to mate but the anatomical parts are not compatible

Gametic Isolation

Prevention of Fertilization

• the sperm of one species will not recognize the egg of another species

  • there may be a different # of chromosomes

Postzygotic Mechanisms

to prevent offspring from growing into healthy and fertile adults

Zygotic Mortality

postzygotic mechanism

• no fertilized zygotes or embryos develop to maturity

Hybrid Invariability

• a hybrid offspring is born but dies soon after

Hybrid Infatility

• a hybrid offspring is born and lives a long life but is infertile

Modes of Speciation

• Allopatric

• Peripatric

• Parapatric

• Sympatric

Allopatric Speciation

species is split by a physical barrier

Peripatric Speciation

small portion of the population is split by a physical barrier

Parapatric Speciation

small portion of the population moves to an adjacent environment - populations keep to themselves (may be overlap)

Sympatric Speciation

a new species evolves from an original species while living in the same region WITHOUT any obvious physical separation

Punctuated Equilibrium vs Gradualism

Punctuated Equilibrium: speciation can occur in sudden bursts followed by long periods of little change

Gradualism: speciation occurs after enough changes have slowly appeared over time

What is the relationship between genetics, evolution and ecology?

Evolution is the outcome of Genetics when species are
required to survive inside an Ecosystem (Ecology)

Gene Pools

all of the alleles and genetic information that exists within a species

Charles Lyell

inspired Darwin

suggested Uniformitarianism

Thomas Malthus

inspired Darwin

suggested Carrying Capacity

Georges Cuvier

founder of paleontology

suggested Catastrophism

James Hutton

suggested Gradualism

Jean Lamarck

suggested Acquired Traits (giraffe example)

Homeostasis

process of maintaining a balance in an organism’s internal environment to sustain life

Physiology

study of how living organisms maintain homeostasis

Molecules → Organelles → Cells → Tissues → Systems → Organisms

Molecules → Organelles → Cells → Tissues → Systems → Organisms

Feedback Loop

Stimulus → Receptor → Control Center → Effector

Negative Feedback Loop

response decreases the effect of the stimulus

Positive Feedback Loop

response increases the effect of the stimulus

Stimulus

change in the environment

Receptor

part of the organism that detects the stimulus

Control Center

part of the organism that decides what to do about the stimulus

Effector

part of the organism that generates the response

Receptor sends information to the control center through an ________ _______.

afferent pathway (towards CNS)

Control center sends instructions out through an ________ ________.

efferent pathway (away from CNS)

Cranial

towards the head

Caudal

away from the head

Superior

higher

Inferior

lower

Posterior

back

Anterior

front

Lateral

closer to the side of the body

Medial

closer to the center of the body

Proximal

closer to the point of attachment (usually referring to limbs)

Distal

farther from the point of attachment (usually referring to limbs)

Sagittal Plane

person is cut symmetrically vertically