Biology Exam #2

**T or F:** There is a universal definition of a species

FALSE

What are the three ways to identify a species?

(1) ^^Biological species concept^^

(2) Morphospecies concept

(3) ==Phylogenetic species concept==

What is the main criteria for the ^^biological species concept^^?

Identify the species thru ^^reproductive isolation^^

* if two different populations do __NOT__ **interbreed** or they **fail to produce** viable & fertile offspring → they are __**distinct species**__

What are the **two isolation mechanisms** for the ^^biological species concept^^?

(1) @@Prezygotic isolation@@

(2) %%Postzygotic isolation%%

What is @@prezygotic isolation@@?

prevents individuals of different species from mating successfully

What is %%postzygotic isolation%%?

the hybrid offspring of matings between members of different species either don’t survive or don’t reproduce

What are the **drawbacks** of the ^^biological species concept^^?

(1) species can’t be identified in fossils or asexual reproducing species

(2) doesn’t apply to species that aren’t close geographically

(3) it’s a complex gradient - not an all-or-nothing concept

What is the main criteria for the morphospecies concept?

Identify the species thru looking at **differences** in size, shape, or other morphological features

What are the __**drawbacks**__ to the morphospecies concept?

(1) May to lead misidentifying species - may not be two different species but rather one species with different phenotypes

(2) can’t identify cryptic species (species with traits other than morphological)

(3) morphological traits are subjective

What is the main criteria for the ==phylogenetic species concept==?

Identify species thru their ==evolutionary history of populations==

* a species is the smallest monophyletic group on tree of life

**Synapomorphy**

a ==trait== that is found in ==certain groups of organisms== and their ==common ancestor==; but is __**missing**__ in more **distant ancestors**

What are the **drawbacks** to the ==phylogenetic species concept==?

(1) carefully estimated phylogenies are available only for a tiny subset of populations on tree of life

(2) tends to recognize more species than morphological & biological - so it complicates naming of species

What do species originate (how does @@speciation@@ occur)?

With…

* %%genetic isolation%%
* genetic divergence

What is %%genetic isolation?%%

Some sort of **barrier** to **gene flow** __isolates__ two populations within a species

* alleles are no longer exchanged without gene flow

What is genetic divergence?

When __mutation, natural selection, or genetic drift__ occurs in **each** of those **isolated** **populations**

* populations begin to evolve independently and become distinct

What is allopatric speciation?

When genetic isolation & genetic divergence are a result of geographical or physical separation

* example: a river forms

What is sympatric speciation?

Random mating turns to non-random mating → then genetic divergence occurs

How does allopatric speciation begin?

(1) Disperal

(2) Vicariance

In terms of allopatric speciation, what is dispersal?

species disperse and colonize

In terms of allopatric speciation, what is vicariance?

individuals don’t move, but rather the land surrounding them does, causing isolation

What causes sympatric speciation?

(1) Disruptive selection - some traits are favored (typically the **extreme** phenotype

(2) Mutation - chromosomal mutation

Polyploidy

having more than two sets of chromosomes

What are the two mechanisms of polyploidy?

* autopolyploidy
* allopolyploidy

Autopolyploidy

Offspring have more than two sets of chromosomes, both which came from __**same**__ parental species

Allopolyploidy

Offspring have more than two sets of chromosomes, but each copy comes from __**different**__ species

What happens when isolated populations come back into contact?

* **Fusion** of populations
* **Extinction** of one population
* **Reinforcement** of divergence
* **Hybrid zone** formation
* Formation of **new species**

What is reinforcement of divergence?

When isolated species come back into contact, they still won’t breed

What type of group on a phylogenetic tree are protists?

paraphyletic

**T or F:** Protists are eukaryotes

T → protists are @@**EUKARYOTIC**@@

Explain the process of the origin of the mitochondria.

Through the Endosymbiosis Theory -


1. Host cell surrounds and engulf bacterium
2. Bacteria lives within host cell
3. Endosymbiosis = host cell supplies bacterium with protection and carbon compounds while bacterium supplies host cell with ATP

Mitochondria are the same size as __________

proteobacterium

Mitochondria replicate by ______, as do bacteria

fission

What are three pieces of evidence for the origin of mitochondria?

1. have their own ribosomes (make their own too)
2. have double membrane
3. have their own genome (circular molecules)

Explain the process of the origin of the chloroplast.

Through Secondary Symbiosis -


1. Photosynthetic protist (protists with chloroplast) is engulfed by host cell
2. Nucleus from photosynthetic protist is lost
3. Organelle has four membranes

Explain the process of the origin of the nucleus and endomembrane system.

1. Infoldings of plasma membrane surround the chromosomes
2. Eukaryotic cell arises with infoldings forming nuclear envelope and ER

What are two morphological innovations?

1. cytoskeleton
2. multcellularity

**T or F:** Multicellularity is about specialization, not just about many cells clumped together

TRUE

What are three ways that protists obtain food?

1. Ingestive feeding
2. Absorptive feeding
3. Photosynthesis

What is ingestive feeding?

Eating live or dead organisms or scavenging on organic debris

What is absorptive feeding?

Absorbing nutrient molecules directly from the environment through the plasma membrane (usually through transport proteins)

If an absorptive species damages its host it is called a _________

parasite

T or F: Protists that engage in ingestive and absorptive feeding are heterotrophs

TRUE

Protists that produce their own organic compounds through photosynthesis are _________

autotrophs

What is the photosynthesis equation?

Gametes always ______

fuse

Meiosis always leads to __________ in chromosome number

REDUCTION

Mitosis leads to *__________* in chromosome number

INCREASE (or stays the same)

What is an advantage of asexual reproduction?

Offspring are genetic clone of parent

What are two disadvantages of sexual reproduction?

1. have to find a mate
2. offspring is only 50% of parent

**T or F:** Spores fuse during alternation generation

FALSE → they undergo mitosis instead

What are the two generations in the process alternation of generations?

Sporaphyte & gametophyte

Sporaphytes always produce _____

spores

Meiosis goes from ______ to N

2N

Gametes are always ______ (2N or N)

N

What are similarities amongst green algae and land plants?

* both have chlorophyll a & b
* thylakoids similar
* cell wall, sperm, peroxisomes similar
* make starch

What are some of the differences/types of land plants?

* nonvascular plants (mosses
* seedless vascular plants (ferns)
* seed vascular (angiosperms & gymnosperms)

**T or F:** Land plants are a monophyletic group

TRUE

**T or F:** Green algae is a monophyletic group

FALSE → green algae is NOT a monophyletic group

Explain how plants have adapted to life on land through the prevention of water loss.

* Leaves and stems have cuticles (wavy layer)
* Plants have a stomata - an opening that allows for gas exchange

Explain how plants have adapted to life on land through the protection from UV radiation.

Plants have their own “sunscreen”

* thymine dimers
* flavonoids

Explain how plants have adapted to life on land by defying gravity

Plants use cohesion - water sticks to other water molecules and then sticks to the sides of the stem

* water is also pulled up the roots/stem by going towards the sunlight

**T or F:** Nonvascular plants are gametophyte dominant

TRUE

**T or F:** Water is not needed for reproduction of nonvascular plants

FALSE → Water IS needed for reproduction in nonvascular plants

**T or F:** Nonvascular plants have separate male and female gametophytes

TRUE

Do nonvascular plants have specialized water transport tissues?

YES

**T or F:** Seedless, vascular plants are gametophyte dominant

FALSE → they are when they are young, but are SPORAPHYTE dominant when mature

Do seedless, vascular plants have separate male and female gametophytes?

NO

What is the main difference between @@homospory@@ and %%heterospory%%?

@@Homospory@@ means @@ONE@@ type of spore is produced, while %%heterospory%% means %%TWO%% types of spores are produced

What are the two types of heterspory?

Microsporangia & megasporangia

Microsporangia

produce microspores which develop into male gametophytes (pollen)

Megasporangia

produce megaspores which develop into female gametophytes

What are three things that the evolution of the seed allowed for?

* allows protection of the embryo
* allows embryo to disperse away from parent
* allowed adaptive radiation

What are seed, vascular, **non-flowering** plants called?

Gymnosperm

What are the male parts of the flower called?

stamen

What does the stamen contain?

Anther

What is the anther?

contains microsporangia and is the site of pollen production

What is the female part of the flower called?

carpel

What does the carpel contain?

stigma, style and ovary

The ovary contains __________ which hold megasporangia

ovules

What are seed, vascular, **flowering** plants called?

angiosperm

Angiosperm have _________ fertilization

double


1. endosperm
2. zygote

What is an endosperm?

Is 3N & forms nutritive tissue in seed

**T or F:** Gymnosperms and angiosperms require water for fertilization

FALSE → NO water needed

Seeds provide ___ & ____ so the seed can live separate from sporaphyte

food & protection

**T or F:** Pollen is sperm

FALSE → pollen is NOT sperm, but produces it

Fruit

ripened ovary, encloses a seed

Within angiosperms are ____ and _____

monocots and dicots

Dicots are a ___ group, and monocots are a ____ group

monophyletic and paraphyletic

cotyledon

first leaf

Monocots means _____ first leaf (cotyledon)

one

Dicots means _____ first leaf (cotyledon)

two

What are some other key differences between monocots and dicots?

Monocots → vascular tissues are scattered, parallel veins, flower petals multiples of 3

\
Dicots → vascular tissues are in circular arrangement, branching veins, petals in multiples of 4 or 5

What defines “animals”

* multicellular
* no cell walls
* heterotrophs (usually ingestive)
* motile (can move at some point)

**T or F:** “Animals” is a monophyletic group

TRUE

diploblasts

embryos have 2 tissue types

What are the 2 tissue types in a diploblast?

ectoderm layer & endoderm layer

triploblasts

embryos have 3 tissue types

What are the 3 tissue types in a triploblast?

1. ectoderm (skin & nervous system)
2. mesoderm (circulatory, muscle, bones, organs)
3. endoderm (lining of digestive tract)

**T or F:** Protosomes and deutersomes are an example of a triploblast

TRUE

Cephalization

evolution of a head