Final Iclicker Review

Question 1

Which of the following could distinguish a prokaryotic from a eukaryotic cell?

Answer 1

Mitochondria

ALL cells have plasma membranes, DNA, cytosol, ribosomes. Plants and prokaryotes have cell walls, but animal cells do not. Only eukaryotes (animals, plants, protists, fungi) have mitochondria.

Question 2

Which of the following is unique to an atom of a particular element?

Answer 2

Number of protons = atomic number

The number of protons an atom possesses identifies what element that atom is from. If you change the number of protons, you change the element.

Question 3

What type of bond must occur first in order for the second type to occur?

Answer 3

Polar covalent first and hydrogen second

In order to have hydrogen bonds occur, for example between 2 molecules of water, each water molecule must have unequal areas of charge differences caused by the internal polar covalent bonds. Polar covalent bonds form when the atoms involved in a covalent bond have unequal electronegativity values.

Question 4

One of the main reasons carbon is the atom that defines organic molecules (i.e. Those that make up living organisms.) is because carbon has: (Note: Not asking what statement is true, just which one makes carbon “special”)

Answer 4

The ability to form 4 covalent bonds.

Atoms of other elements can do the other things (isotopes, rings, double bonds, bonding with H) but the fact carbon has a tetravalence makes it very versatile.

Question 5

What distinguishes one macromolecule from another is:

Answer 5

The identity of the individual monomers that make up their polymer structure.

While many details are the same (such as all have the same basic dehydration synthesis reactions to join monomers), each of the major macromolecules have different monomers which identify the type of macromolecule. Carbohydrates have monosaccharides, proteins have amino acids and nucleic acids have nucleotides. Although the lipids don’t have a classic monomer, they do have a recognizable non-polar region that distinguishes them.

Question 6

True or False: Individual organelles inside eukaryotic cells can function outside the cell.

Answer 6

False

All of the individual organelles have very specific functions that work together, in many cases with other organelles. They are all dependent on being inside the eukaryotic cells, requiring energy to accomplish their specific tasks. The compartmentalization by membranes of the interior of the eukaryotic cells allow these functions to occur.

Question 7

Probably the most important feature of the cell membrane is: (Note: Other statements might be true but asking for the most important one)

Answer 7

Phospholipids have an amphipathic nature.

Amphipathic means the molecule has both polar and non-polar regions. Phospholipids have polar phosphate heads and non-polar fatty acid tails. This allows them to form a stable bilayer when in aqueous (water based) environments such as what is inside and outside the cell.

Question 8

True or False: Enzymatic reactions are only needed for anabolic pathways.

Answer 8

False

Many types of chemical reactions require enzymes, even those that are exergonic and part of catabolic pathways. EVERY chemical reaction requires some activation energy to break apart the reactant molecule’s bonds and the amount needed is reduced by the presence of an enzyme. This is independent from any energy that might ultimately be released by an exergonic reaction.

Question 9

True or False: Cell respiration occurs in plants.

Answer 9

True!!!!!!!!!!!!

Remember, plants “eat” by photosynthesis, thus gaining stored chemical energy just like us BUT they then need to use cell respiration to break down that energy to make ATP.

Question 10

The unique thing plants (or all producers) do during photosynthesis that consumers such as ourselves can not do is:

Answer 10

Fix inorganic carbon into organic carbon

The ability to bring new sources of inorganic carbon (i.e. carbon dioxide) into the building of organic molecules is unique to the producers. This process is called carbon fixation, and plants use light energy to accomplish this task.

Question 11

The process of mitosis creates:

Answer 11

Both A. and C. Somatic, diploid cells

Remember mitosis is all about duplicate DNA 1x and divide 1x which ensures 2 new cells are genetically identical to each other and to the parental cell that underwent mitosis.

Question 12

The process of meiosis creates:

Answer 12

Both B. and D. Haploid, gametes.

Remember meiosis is all about duplicate DNA 1x and divide 2x which ensures 4 new cells that are genetically NOT identical to each other and to the parental cell that underwent meiosis. The haploid nature guarantees our gametes will only have one copy of every gene, and other events such as crossing over and independent assortment during meiosis leads to genetic variation.

Question 13

A potentially correct genotype is which of the following?

Answer 13

AABB

A genotype must have TWO copies of each gene. This particular genotype is telling you this individual is homozygous dominant (i.e. both alleles are dominant) for both genes A and B. A gamete would only have one copy of each gene so 100% of the gametes for this individual would be AB.

Question 14

If a human egg that has an extra 21st chromosome is fertilized by a normal sperm, the resulting embryo would have what chromosome number?

Answer 14

47

The aneuploid egg would be n + 1 which for humans is 23 + 1 thus 24. The normal sperm would be n = 23. Fertilization would produce an embryo that is 2n + 1 or 24 + 23 = 47.

Question 15

Which complementary pair of DNA strands is correct?

Answer 15

5’ A T A C G 3’
3’ T A T G C 5’

The correct base pairs are matched up (A-T, C-G), the polarity is antiparallel and thymine (T) is used and not uracil (U) which would only be in RNA.

Question 16

The correct sequence of events is which of the following?

Answer 16

Transcription of DNA to RNA to the translation of RNA to amino acids.

This is the central dogma of protein synthesis. The DNA genome holds the genetic code that is faithfully replicated during cell division. Individual coding regions for each gene are transcribed from DNA to RNA nucleotides (transcription) and then the RNA nucleotides are translated into the correct order of amino acids to form the primary structure of a

Question 17

True or false: Eukaryotic cells have operons.

Answer 17

False

Only prokaryotes have the operon gene regulation system of one promoter/operator which controls the expression of multiple genes that create gene products that have a related function. Eukaryotes do not have a similar system but regulate gene expression through a variety of other ways such as alternative gene splicing, methylation of DNA, histone wrapping, etc.

Question 18

A vestigial structure is evidence of:

Answer 18

Homology

Vestigial structures are typically those that modern species possess but have no obvious current use. They are thought to be “leftover” from evolution from a previous ancestor which may have had a use for the structure.

Question 19

In a population of wild flowers, the are 2 alleles for flower color: dominant red (R) and recessive white (r). There are 25% white flowers in the population. What is the frequency of the red allele?

Answer 19

0.5

White is the recessive phenotype and there are 25% white flowers. This means q2 = 0.25 so q = 0.5. p will equal 1 – 0.5 or 0.5.

Question 20

Two populations of birds living in the same habitat slowly evolve into 2 different species based on feeding preferences even though their gene pools could potentially mix. This is most likely an example of:

Answer 20

Sympatric speciation

Sympatric speciation, while rarer, can occur when there is no geographical barrier separating the populations.

Question 21

Which of the following scientists would have most likely SUPPORTED Darwin’s theory of descent with modification?

Answer 21

Correct answer: Lyell: Uniformitarianism: Slow, gradual change in geology

Others:

Aristotle: Scala naturae, organisms unchanging

Cuvier: Catastrophism, sudden changes in geology & organisms

Linnaeus: Classification system but believed in divine reasons

Lamarck: Inheritance of acquired characteristics

Question 22

Can an individual organism evolve?

Answer 22

No

While individuals may possess inheritable traits that increase their survival rate and allow them to pass those traits on to their offspring, the individuals themselves do not evolve. Evolution by definition involves the change in genetic composition in a population over time.

Question 23

Using this evolutionary tree, do amphibians have an amnion?

Answer 23

No

Amnion developed in an ancestor of mammals, lizards/snakes, crocodiles and the birds after a branch point separating amphibians.

Question 24

The Australian honey possum has a long tongue that can take nectar from flowers and looks very similar to structures butterflies and hummingbirds have to do the same task. Do you think this is an example of homology or convergent evolution (analogy)?

Answer 24

Convergent evolution

None of these species are closely related nor do they most likely share a common ancestor who would have had this feature. They each evolved a similar structure separately that is matched with the same function which is convergent evolution.

Question 25

Statement: “Humans evolved from monkeys.” Do you think this is an accurate statement about evolution?

Answer 25

The theory of evolution does NOT say humans evolved from monkeys. It does says we both evolved from a common ancestor that lived millions of years ago. Other human like species also evolved from this common ancestor (Ex. Homo erectus) and they went extinct while Homo sapiens lived on with a few other primates such as monkeys, apes and other related species.

Question 26

What event in sexually reproducing organisms does NOT directly lead to potential increased genetic variation in offspring?

Answer 26

Duplication of chromosomes in the S phase

Question 27

Gene A has 2 alleles and one is dominant (A) over the other (a). In a population of 1,200 individuals, there are 500 homozygous dominant individuals, 400 heterozygous individuals and 300 homozygous recessive individuals. What is the frequency in percentage for the recessive allele for this gene?

Answer 27

42%

1,200 individuals = 2,400 alleles in total

a allele: 300 aa x 2 = 600 a’s from aa + 400 a’s from Aa = 1000 a’s

Frequency of a allele is therefore 1000/2400 = 42%

Question 28

In a population of pigs, there are 4 black pigs and 12 pink pigs. The pink allele is dominant and the black allele is recessive. What is the percentage of the pigs that are heterozygotes?

Answer 28

50%

Question 29

Is genetic drift adaptive?

Answer 29

No

Remember, if something is adaptive, natural selection dictates that certain alleles will preferentially survive over others. Genetic drift has no such mechanism and certain alleles surviving over others is purely chance.

Question 30

Is this image an example of INTRA- or INTER- sexual selection?

Answer 30

Intersexual =

Female mate choice

Question 31

Does the term “hybrid” in the origin of species mean the same thing as “heterozygote”?

Answer 31

No

A hybrid here means the mating of 2 different SPECIES. Heterozygote for a particular gene means an individual has 2 different alleles for that gene because its parents were contrasting true breeders. Ex. AA x aa produces hybrid/heterozygotes for that ONE locus.

Question 32

The offspring of a male lion and a female tiger is called a LIGER. They are only found in captive zoo populations. Ligers are typically sterile although there have been a few cases of ligers producing weak offspring by mating with lions. They are therefore not considered by most biologists as a new species. Which of the following barriers prevents them from becoming a new species?

Answer 32

Reduced hybrid fertility

Question 33

Millions of years ago, there was a single species of squirrel that lived in the desert where the Grand Canyon currently lies. Today, there are 2 distinct species of squirrels, one living on the southern rim of the canyon and the other living on the northern rim. This is an example of _________.

Answer 33

allopatric speciation

Once the vast Grand Canyon formed, terrestrial species such as squirrels could not easily maintain gene flow between populations on either side of the canyon thus eventually evolving into different species. This type of speciation due to geographic isolation is allopatric.

Question 34

The Great African lakes such as Lake Malawi are home to an incredibly diverse number of species of cichlid fish, once thought to number 100’s of different species. Due to recent human impact on the lake’s ecology, the stresses on many species has caused them to successfully hybridize thus reducing the overall number of individual species. This is an example of:

Answer 34

Fusion

If 2 species hybridize so successfully that neither original species exists anymore, this is fusion and causes a loss of species diversity.