Biology

Biology Unit 5 Study Guide: Evolution

Biology Unit 5 Study Guide: Evolution

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Biology Study Guide Book just published and on sale! :  Study Guides: Biology Unit Review Practice Questions and Answers 
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BIOLOGY UNIT 4 Study Guide: Genetics, MeisosiS, DNA, and Protein Synthesis

What does it mean to say that organisms evolve?

 

After his visit to the Galapagos Islands, Darwin came up with the theory of evolution.  This theory stated that organisms change over time.  The way that organisms change is through the process of natural selection.

 

In order for natural selection to work, four things must be true:

  1. organisms produce many offspring – struggle for survival
  2. variations exist in any population
  3. individuals with favorable variations survive
  4. favorable variations are inherited by offspring

If natural selection favors one extreme of a trait, then this is called directional selection.  For instance, if taller giraffes were better able to reach the leaves in trees, then over time the population of giraffes would change to be taller.

 

If natural selection favors both extremes of a trait, then this is called disruptive selection.  For instance, if small deer are able to run quickly to escape predators and large deer are able to fight off predators, the over time the population would contain more small and large deer.

 

If natural selection favors neither extreme of a trait and it’s better to be average, then this is called

stabilizing selection.  For instance, if dark and light clams are easily seen by birds against gray rocks, then over time the population would contain more gray.

 

If a population is not evolving, but rather maintaining the same frequencies of genetic alleles, the population is said to be at genetic equilibrium.

 

When organisms evolve to look like another organism (mimicry) or blend into their environment (camouflage) these are examples of adaptations.

 

 

What is the difference between convergent and divergent evolution?

Convergent Evolution

Divergent Evolution

unrelated organisms evolve to have similar features because of similar environments

 

closely related organisms evolve to form different species (adaptive radiation)

Is it possible for organisms to NOT evolve?

If a population is not evolving, but rather maintaining the same frequencies of genetic alleles, the population is said to be at genetic equilibrium.  This is pretty difficult to maintain because the following five things must be true about the population in order for it to not change:

  1. large population
  2. random mating
  3. no mutations
  4. no movement in or out of the population
  5. no natural selection
Biology Study Guide Book just published and on sale! :  Study Guides: Biology Unit Review Practice Questions and Answers 
Biology Unit 1 Study Guide: Ecology and Scientific Method
Biology Unit 2 Study Guide: Basic Building Blocks of Life
BIOLOGY UNIT 3 STUDY GUIDE: CELL ENERGY – PHOTOSYNTHESIS AND CELLULAR RESPIRATION
BIOLOGY UNIT 4 Study Guide: Genetics, MeisosiS, DNA, and Protein Synthesis

How do new species develop?

 

The process of getting several different species from one original species is called speciation.  In order for this to happen, the first thing that must happen is reproductive isolation.  In other words, something must happen to divide the original population so that they can no longer mate with each other.  One way that this occurs is if the population is physically separated by land or by water.  This is known as geographic isolation.  They might also be separated by different mating behaviors (behavioral isolation) or separated by different mating times (temporal isolation).

 

Next, each population evolves independently, according to their environment and available alleles in their gene pool.  In a small population, evolution can occur more quickly.  When there are random changes in allele frequency (like a small group beginning a new colony or a natural disaster randomly takes out a part of the population), this can create genetic drift.  Over time the alleles found in the remaining population would become more common and therefore look different from the original group.

 

The two populations are considered two different species if they can no longer mate and produce fertile offspring.

 

What evidence do we have that evolution occurs?

 

Evidence for Evolution

Evidence

How it Supports Evolution

fossil record

 

shows changes in species over time, different organisms appear at different times, shows extinctions

embryology

 

different organisms have similar embryos, showing likelihood of common ancestor

geographic distribution

(biogeography)

shows convergent evolution and adaptive radiation

comparative anatomy

 

vestigial structures indicate ancestor organism – species change over time; homologous structures show divergent evolution

DNA, RNA comparison

 

organisms more closely related share larger percentage of genome

While the evolution of new species of plants or animals may take millions of years, it is easy to see the evolution of new variations of bacteria and viruses within a very short period of time because of their very fast rate of reproduction.  With bacteria, we have seen the evolution of resistance to antibiotics.

 

  1. What are antibiotics? Poisons specific to bacteria that work by stopping a process necessary for the life of the cell (inhibit metabolism, break down cell membranes or walls, break down necessary enzymes, etc.)
  1. Why and how have bacteria become resistant to antibiotics? Overuse of antibiotics have led to resistance.  With exposure to antibiotics, natural mutations will occur by chance providing some bacteria the ability to resist or counteract the antibiotic.  Those bacteria that survive will reproduce and pass on this ability to their offspring changing the population to bacteria that are able to resist the antibiotic.
  1. Why don’t antibiotics work on viruses? Viruses are not living – they do not have cell walls, undergo metabolism, use energy, etc. – all of the things that antibiotics work to destroy.

With viruses (as well as bacteria), we have seen the evolution of resistance to vaccinations.

 

  1. What is a vaccination and how does it work? An injection of a dead or weakened pathogen that is used to stimulate the immune system.  Your body fights the pathogen and leaves memory cells so that if it encounters the pathogen again it can fight it more quickly.
  1. Why do people need a new flu vaccination every year? Your body is only able to recognize the pathogen you were vaccinated for.  The influenza virus mutates so quickly that it produces new strains that your body will not recognize and you will not have an immune response ready for it.
  1. Why do some vaccinations work with just one shot? Pathogens that can be stopped with just one vaccination are pathogens that evolve slowly and do not mutate very much so your body will still recognize it even many years later.
Biology Study Guide Book just published and on sale! :  Study Guides: Biology Unit Review Practice Questions and Answers 
Biology Unit 1 Study Guide: Ecology and Scientific Method
Biology Unit 2 Study Guide: Basic Building Blocks of Life
BIOLOGY UNIT 3 STUDY GUIDE: CELL ENERGY – PHOTOSYNTHESIS AND CELLULAR RESPIRATION
BIOLOGY UNIT 4 Study Guide: Genetics, MeisosiS, DNA, and Protein Synthesis

 

How do scientists think life began on Earth?

  1. Scientists believe that early Earth must have been a place that current living things wouldn’t be able to survive because it was filled with gasses such as carbon monoxide and was missing O2 (oxygen).
  2. Miller and Urey’s experiment demonstrated that from these early conditions and gases, it may be possible for amino acids and nucleotides to form.
  3. These small organic monomers could have joined to form larger polymers, which make up our current biomolecules.
  4. RNA was probably the first self-replicating molecule.
  5. Perhaps the earliest version of a cell was a simple organic bubble known as a proteinoid microsphere.
  6. Photosynthetic bacteria started releasing oxygen into the atmosphere.
  7. The endosymbiotic theory states that eukaryotic cells are probably the result of symbiotic relationships between prokaryotic cells. Evidence for this is:
    1. mitochondria and chloroplasts contain DNA similar to bacteria
    2. they have ribosomes and membranes similar to bacteria
    3. they reproduce by binary fission like bacteria

How did humans evolve?

Fill in the chart to show important evolutionary developments for hominid evolution:

Key Evolutionary Developments

Importance to Evolution

bipedalism

 

hands free, distance vision, intimidation

opposable thumb

 

fine motor skills

development of tools

 

able to get to foods w/ more fat/energy

larger brain

 

increase in intelligence, complex social interactions

larger pelvis

 

better for upright walking, bigger babies

How do we organize organisms based on evolution?

Number the following in the correct order of appearance:

            _7___  Placental mammals appear                __8__   Humans appear

            _4___   First land plants appear                     __6__   Reptiles appear

            _5___   First amphibians appear                    __1__   Prokaryotes appear

            _2___  Protists appear                                    __3__   Jellyfish appear

 

 

Classification of organisms:

Carl Linnaeus is known as the “father of classification”.  Today organisms are divided into three domains, which are further broken into kingdoms.  Fill in the chart below:

 

Domains

Bacteria

Archaea

Eukarya

Kingdoms

Eubacteria

Archaea

Protists

Plant

Fungi

Animal

Distinguishing characteristics

unicellular

prokaryote

peptidoglycan in cell wall

unicellular

prokaryote

no peptidoglycan in cell wall

extreme living conditions

Mostly unicellular
eukaryote

multicellular

autotroph

Mostly multicellular

heterotroph

absorbs nutrients

Multi-

cellular

hetero-

troph

ingests nutrients

Biology Study Guide Book just published and on sale! :  Study Guides: Biology Unit Review Practice Questions and Answers 
Biology Unit 1 Study Guide: Ecology and Scientific Method
Biology Unit 2 Study Guide: Basic Building Blocks of Life
BIOLOGY UNIT 3 STUDY GUIDE: CELL ENERGY – PHOTOSYNTHESIS AND CELLULAR RESPIRATION
BIOLOGY UNIT 4 Study Guide: Genetics, MeisosiS, DNA, and Protein Synthesis

 

The scientific name for organisms is always the genus followed by the species.  For instance, humans are known by the name Homo sapiens.  This two-name method of labeling organisms is known as binomial nomenclature.

 

The order of classification after domain and kingdom is phylum, class, order, family, genus, species.  One way to remember this order is the statement Kids Playing Chess On Freeway Get Squished or King Philip Came Over For Good Spaghetti.

 

seljalandsfoss-most-instagrammed-waterfalls-world-1200x855

Check out:

 
Biology Study Guide Book just published and on sale! :  Study Guides: Biology Unit Review Practice Questions and Answers 
Biology Unit 1 Study Guide: Ecology and Scientific Method
Biology Unit 2 Study Guide: Basic Building Blocks of Life
BIOLOGY UNIT 3 STUDY GUIDE: CELL ENERGY – PHOTOSYNTHESIS AND CELLULAR RESPIRATION
BIOLOGY UNIT 4 Study Guide: Genetics, MeisosiS, DNA, and Protein Synthesis

What happens when oxygen is not available for cellular respiration?

 

If oxygen is not available, then the electron carriers NADH and FADH2 are unable to release their electrons and pick up more.  When this happens, the process of the

Kreb cycle and electron transport chain cannot make ATP.

 

In order to continue making ATP without oxygen, some cells can switch to a process called fermentation.  This relies on glycolysis to make ATP.  Yeast and bacteria will then convert pyruvic acid to ethanol and CO2 while muscle cells in animals will convert it into lactic acid in order to regenerate NAD+.

 

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