Final Bio Exam

Explain in detail how natural selection works.

2 Observations

1. Variations - Differences in DNA that are inherited

2. Competition - Always more individuals born that survive - because the environment can only support so many

2 Inferences

1. Favorable traits increase the probability of survival and reproduction → fitness

2. Over time more individuals have the favorable trait

What is the difference between homology and analogy?

Homology - Similarities due to a common ancestry

Analogy - Similarities due to a common environment

Explain how homology and analogy can be used for evolution.

Divergent evolution - Share common ancestry, change over time to adapt to your environment

Convergent Evolution - Different common ancestor but look the same

Vestigial structures

Does not have the original function but still function due to homology

What does it mean for a population to be in Hardy Weinberg Equilibrium?

Allele frequencies (p and q) stay the same every generation (if no evolution occurs)

What assumptions need to be in place for a population to stay in HWE?

1. No mutation

2. No migration → no gene flow

3. No natural selection → no evolution

4. Large population → no genetic drift

5. Random mating

What is microevolution?

Allele frequencies change in every generation

Name and briefly explain four ways to cause microevolution.

1. Mutations - Changes in DNA → rare → very slow by itself to cause change → usually mutations work with other forces

2. Gene Flow - Similar to migration → move alleles from the population to the next

3. Genetic Drift - Random changes that occur in small populations

4. Natural Selection - Only way for adaptive evolution to occur → better fit to your environment

Briefly explain the examples of postzygotic barriers presented in the text.

1. Reduced hybrid viability - less likely to survive

2. Reduced hybrid fertility - less likely to reproduce

3. Hybrid Breakdown - start out viable/fertile → after a few generations → decrease viability/fertility

Name and explain two major ways speciation can occur.

1. Allopatric Speciation - Form a new species due to geographic barriers

2. Sympatric Speciation - New species form without a geographical barrier → everyone is in the same place but there is no gene flow between species

Explain three ways in which sympatric speciation may occur.

1. Sexual Selection - Choose mates based on certain criteria

2. Habitat Differentiation - Live in the same space but different niche (live on different tree species)

3. Polyploidy - More than two sets of chromosomes

What is autoploidy and alloploidy?

Autoploidy - Extra chromosomes come from own species

Alloploidy - Extra chromosomes come from a different species

What is the first eon in the geological record?

Hadean eon - started about 4.6 billion years ago

Explain what it was like on Earth during the hadean eon and why it came to an end.

Hot, water vapor, gases, lightning. Nothing alive yet. When the earth cooled → liquid water formed → ended hadean eon - 4 bya

What is the second eon in the geological record?

Archean - Started 4 billion years ago

What evolved during the second eon?

Prokaryotes evolved → first fossils are stromatolites - bacteria trapping minerals

What ended the Archean eon?

Oxygen Revolution - 2.5 billion years ago, huge increase of oxygen on earth → likely due to organisms doing photosynthesis → led to a big extinction of prokaryotes for whom oxygen was toxic

What is the third eon in the geological record?

Proterozoic - Began 2.5 billion years ago

What evolved during the Proterozoic eon?

Eukaryotes evolved → plasma membrane forms organelles like ER, Golgi

What is the Endosymbiont Theory?

Origins of mitochondria and chloroplasts used to be bacteria

What ended the Proterozoic eon?

Cambrian explosion - 500 million years ago → all modern animal groups appeared

What is the fourth eon in the geological record?

Phanerozoic - Current eon starting -500 million years ago

What evolved during the Phanerozoic eon?

Cambrian explosion resulted in a lot of new animal groups

Coevolution

2 species evolving together

How do reproduction and mutation work together to create genetic diversity in prokaryotes?

Binary Fission - Bacteria reproduce asexually making identical copies (clones) → this does not create genetic variation

-Even though mutations are rare, they spread quickly due to the rapid reproduction of bacteria (fast as 20 minutes) → genetic variation

Genetic Recombination

Combine DNA from 2 different bacteria (can be different species) → also increases genetic variation

Name and explain the three ways bacteria can undergo genetic recombination.

1. Transformation - Bacteria picks up donor DNA from the environment

2. Transduction - The donor DNA is delivered by a virus

3. Conjugation - Donor bacteria has a plasmid

Plasmid

Extra DNA outside of main chromosome → makes a pilus - protein tube. It sends DA through the pilus to the recipient

Symbiotic Relationship

2 organisms interacting

Explain the three symbiotic relationships bacteria can form

1. Mutualism - both benefit

2. Commensalism - one benefits, the other is NOT harmed/does NOT benefit

3. Parasitism - one benefits, one is harmed

What do the supergroup Excavates have in common?

All either have a unique flagella or modified mitochondria (different from most)

What do supergroup SAR clade eukaryotes have in common?

SAR Clade - related by DNA analysis

Name the three major subgroups of the SAR Clade.

Stramenopiles, Alveolates, Rhizarians

What do stramenopiles have in common?

Most have a smooth and hairy flagella

What do alveolates have in common?

Have alveoli - little sacs under the plasma membrane

What do Rhizarians have in common?

Many amoebas with threadlike pseudopods - used to move and eat

What groups are in the supergroup Archaeplastidae?

All do photosynthesis and ate the same cyanobacteria (Endosymbiont Theory)

Describe the Amoebazoans in the supergroup Unikonta.

Amoebas with lobelike pseudopods

Besides the alternation of generation, what are other four derived traits of land plants?

1. Embryophytes - Plant embryos (babies) stay in female gametophytes after fertilization → protection, nutrients, prevent dehydration

2. Spirangia - Where spores are made on sporophyte

3. Gametangia -Where gametes are made on gametophyte

4. Apical Meristems - Where cell division takes place → grow roots, leaves, etc.

What is the antheridia and archegonia?

Archegonia - Eggs are made here

Antheridia - Sperm are made here

Explain five derived traits of seedless vascular plants.

1. Sporophyte is dominant (always there - leafy parts). Gametophyte is small, independent of sporophyte

2. Vascular tissue - move food/water long distances

3. Roots - Anchor plant, absorb water/food and transport it, stronger than rhizoids

4. Leaves - More surface area to absorb sunlight

5. Sporophylls - Leaves with spores

What is xylem and phloem?

Xylem - transport water/minerals

Phloem - transport water/food

How is the production of eggs and sperm different in seeded vascular plants?

Egg Production

Ovule - where eggs are made, protects embryo, develops into seeds

integument (skin) - protective outside layer, becomes seed coat

megasporangium - where megaspores are made → leading to the egg

Sperm Production

Pollen - Make gametophyte that makes sperm

-No more flagellated sperm → no more water needed for swimming

-Use pollination → pollen travels to egg → makes a pollen tube for sperm to travel

What is a seed?

Plant embryo, nutrients, seed coat (protection)

What are the evolutionary advantages of seeds?

Built in food supply, extra protection, great for dispersal - spreading around

Angiosperms

Seed plants with flowers and fruit

What are two key adaptations of Angiosperms?

1. Flowers - sexual reproduction and attracts pollinators

2. Fruit - develops around seeds from the ovary, help with dispersal

Describe the process of sexual reproduction in fungi

1. Fungi release pheromones - chemicals into environment by hyphae → determine if they are different mating types.

2. Plasmogamy - cytoplasm fuses, nuclei did not yet!

3. Karyogamy - nuclei fuse → diploid zygote

What is heterokaryon?

2 different nuclei in one cell → can stay like this for centuries

What do microsporidians and cryptomycetes have in common?

Both microsporidians and cryptomycetes are very old, parasites and closely related by DNA

How do microsporidians and cryptomycetes differ?

Microsporidians - Infect other organisms with a harpoon

Cryptomycetes - yeast with zoospores - spores with flagella (need water for spore to swim), infect fungi and algae

What is a chytrid?

Multicellular fungi with zoospores, can be parasite (amphibian killer)

What is a zoopagomycetes?

Zoopagomycetes - Uses a zygospore - sexually reproduced spore with extra protection

-many parasites of fungi and animals

What is a mucoromycota?

Includes mold and glomeromycotas molds sexually reproduce using zygospores

What is a Glomeromycota?

Mycorrhizae - relationship (mutual) between fungi and root cells. Fungi get carbs and plants get extra nutrients and minerals.

Arbuscular - Fungi go inside root cells

Compare and contrast the reproductive structures of Basidiomycota and Ascomycota.

Basidiomycota - sexually reproduce using basidiocarp - mushroom

Ascomycota - sexually reproduce using ascocarp

Both use asexual spores called conidia

Symmetry

Do the halves match if you cut vertically

Name and explain the two major types of symmetry.

Radical - Any vertical cut results in matching halves

Bilateral - only one way for the two halves to match

Asymmetry

No symmetry

Embryotic tissue layers

Tissue layers that develop in gastrula

What is the difference between a diploblast and a triploblast?

Diploblast - two layers (nidarians)

endoderm - inner layer

ectoderm - outer layer

Triploblasts - three layers - all other animals

endoderm - turns into digestive tract/structures

mesoderm - middle layer, - muscle, bones

ectoderm - skin and nerves (central nervous system) brain + spinal cord

What does it mean to have a true body cavity?

Only triploblasts can have a body cavity fluid or air filled space

Coelom

True body cavity - cushion/separate organs, protective lining, made from mesoderm

Is there any other kind of body cavity you can have?

Psuedocoelom - Body cavity without lining, less organized, made from mesoderm and endoderm

Aceolom - triploblasts without body cavities

Explain the three categories that define a protostome versus a deuterostome.

1. Cleavage - rapid cell division that forms the embryo

2. Coelom Formation - how true body cavity forms

3. Fate of Blastspore - first opening to the outside → mouth or anus

What makes sponges different from all other animals?

Sponges are basal animals - oldest living animals, no tissues, no symmetry, no body cavities

What makes cnidarians different from all other animals?

All animals except sponges are Eumetazoa - true tissues. Cnidarians - only animals that are radial diploblasts

What do all lophotrochozoans have in common?

Lophotrochozoans - based on DNA

Lophophores - ciliated tentacles

Trocophores - ciliated larvae

Some have lophophores, some have trocophores some have neither

What are the four key characteristics of chordates?

1. Notochord - structural support, humans → becomes our backbone

2. Nerve Cord - humans → becomes our central nervous system → brain and spinal cord

3. Pharyngeal slits - filter feed, respiration (gills), humans → part of neck/ear area

4. Tail - movement, stability, or very small in humans → coccyx

What is a vertebrate?

Animals with a backbone

What is a gnathostome?

Vertebrates with a jaw- if aquatic → lateral line system - sense vibrations

What is a tetrapod?

Gnathostome with 4 limbs with digits

What is an amniote?

Tetrapod with a terrestrial egg (lay on land)

What is a mammal?

Amniotes with hair and mammary glans

What is a primate?

Grasping hands and depth perception → helps to live in trees