ISB Exam 3

mtDNA

. inherited by all children only from their mother

What type of seed plant is likely to rely on hungry animals to spread its seeds? Explain your answer.

Angiosperms or Flowering plants. Because this is the only group that has their seeds in a fruit. Hungry animals would eat the fruits and help disseminate the seeds to new locations.

_________________ and ______________ are two branches of life that has prokaryotic cells.

Bacteria and Archaea

Why do beta-lactam antibiotics affect sensitive bacterial cells but not human (or eukaryotic) cells?

Beta-lactum antibiotics interferes with the synthesis of the Peptidoglycan cell wall of bacteria. Eukaryotes including humans do not have a Peptidoglycan cell wall. Therefore, while the beta-lactum antibiotics can kill the sensitive bacteria, it will not affect eukaryotes including humans.

_______________ are a group of plants that are considered to be closest to the plants that first lived on land.

Bryophytes/Mosses

T or F: Archaea are considered to be evolutionally more related to bacteria than eukaryotes.

FALSE

T or F: Given that they make their own food using photosynthesis, plants are the only heterotrophs among all Eukaryotes.

FALSE

T or F: Of the photosynthetic Eukaryotes that live on land, only non-vascular plants such as bryophytes (mosses) need to live in moist environments to assure successful reproduction.

FALSE

What is an advantage of having seeds? (Think about spreading to new locations and whether or not reproduction relies on water.)

Given that seeds provide protection to the embryo and also provides food until it could germinate and make its own food, plants with seeds could spread to new locations and don't need to depend solely on water for successful reproduction.

What is the difference between Gram positive and Gram negative bacteria?

Gram negative bacteria have an additional lipid layer above the cell wall.

What happens to a penicillin-resistant strain of S. aureus in the presence of penicillin?

If the S. aureus bacteria are resistant top Penicillin, it will not have any effect on the cell wall and so, the penicillin resistant bacteria will continue to divide and increase in numbers.

Who is referred to as "Mitochondrial Eve" (mtEve), and when did she live?

Is the single female ancestor whose mitochondrial DNA closely matches to that of the modern humans living in various regions of the world including Asia, Africa, Europe, Australia and the New Guinea.

. List the features that make Lost City a particularly harsh environment for organisms

Low oxygen, High pH (rather caustic), Very high temperatures (80-1000C), High pressure about 2600 feet below the water

Briefly explain two hypothesis that explain evolution of modern humans (Homo sapiens).

Multiregional hypothesis - Ancient humans migrated from Africa about 2 million years ago into Europe and Asia. Over time they evolved into a single species to become modern humans Out of Africa hypothesis - Modern humans first appeared 200,000 years ago in East Africa and spread around the world from there displacing earlier members of the Homo genus

Bacteria can acquire new alleles through two ways. Name these two ways.

Mutations and Gene transfer

Consider the eating habits of fungi. a. Can fungi carry out photosynthesis? b. Can fungi ingest their food? c. How do fungi obtain their nutrients and energy?

NO NO They secrete enzymes out of the body and digest/breakdown complex food molecules into their subunits and then absorb the subunits along with nutrients into their bodies to be converted into energy.

. How is it that the antibiotics Penicillin and Streptomycin could kill bacteria without affecting Human cells?

Penicillin kills the bacteria by interfering with cell wall synthesis. The weak cell wall is not able to resist the pressure of water coming into the bacteria cell resulting in cell rupture that kills the bacteria. Human cells do not have a cell wall. Therefore, they are not affected. Streptomycin kills bacteria but entering the cells and binding with bacterial ribosomes to stop them from functioning. When ribosome is not functioning, bacteria are not able to synthesize its proteins, and dies. Ribosomes in the human cells are very different to bacterial ribosomes. Therefore, Streptomycin cannot bund to it and stop its function. Therefore, human cells are not affected.

What happens to a penicillin-sensitive strain of S. aureus in the presence of penicillin?

Penicllin interferes with the synthesis of the peptidoglycan cell wall in S. aureus. When the cell wall is weakened, there is no barrier to control the water coming into the cell through osmosis. This means the bacteria will burst and die.

The cell wall of bacteria are made up of _____________

Peptidoglycan layer

How did the evolution of vascular systems in plants change the landscape?

Presence of the vascular system meant that plants could grow bigger and taller and in less moist environments as long as the soil could provide water that could be transported to the rest of the plant body. This would allow plants to spread into drier areas.

Your roommate has been prescribed an antibiotic for bacterial pneumonia. She is feeling better and stops taking her antibiotic before finishing the prescribed dose, telling you that she will save the remainder to take the next time she becomes sick. What can you tell your roommate to convince her that this is not a good plan?

Stopping the antibiotic without taking the entire course is dangerous because the bacteria that show some resistance to the antibiotic will not be killed and they can then multiply. The next time she takes the same antibiotic, it may not be affective at all. By continuing with all the full dose, you are hoping to wipe out the population of the infectious bacteria.

T or F: Endosymbiosis is a hypothesis that is used to explain how Eukaryotes would have evolved from a common anaerobic ancestor that engulfed photosynthetic bacteria and/or aerobic bacteria.

TRUE

T or F: Eukaryotes are different from Prokaryotes in that Eukaryotes have a nucleus and membrane bound organelles.

TRUE

T or F: The antibiotic Penicillin has the ability to kill bacteria by interfering with its cell wall whereas, Streptomycin kills bacteria by binding to its ribosome and disrupting the function.

TRUE

_____________ were the last animals to arrive on land and include fish, birds, reptiles, amphibians and mammals. However, this group is a small fraction of the total animal diversity on the planet.

Vertebrates

If a single bacterial cell that is sensitive to an antibiotic—for example, vancomycin—is placed in a growth medium that contains vancomycin, it will die. Now consider another single bacterial cell, also sensitive to vancomycin, that is allowed to divide for many generations to become a larger population. If this population is placed into vancomycin-containing growth medium, some bacteria will grow. Why do you see growth in this case, but not with the transferred single cell?

When it is a single cell, that is sensitive, it has no way to resist the antibiotic and so, it dies. During cell division in bacteria as they build a population of cells, DNA can get mutated as the DNA replicates before division. Some of these mutations could provide defense mechanisms for the bacteria to resist antibiotics (by breaking it down using an enzyme, pumping it out of the cell, blocking a binding site etc.).

A major difference between a fern and a confer is a. the presence of seeds and pollen b. the presence of flowers c. the presence of a vascular system d. the ability to carry out photosynthesis e. All of the above

a

According to the out-of-Africa hypothesis of human origins and migration, which group of people should show the highest level of genetic diversity? a. Africans b. Europeans c. Asians d. South Americans e. Australians

a

The evolution of antibiotic resistance is an example of a. directional selection b. diversifying selection c. stabilizing selection d. random selection e. steady selection

a

The term "MRSA" as it is used today refers to a. S. aureus bacteria that are resistant to many antibiotics. b. a collection of skin and other infections caused by a type of bacteria. c. S. aureus bacteria that are found only in humans with certain types of skin infections. d. S. aureus bacteria that are normal residents of human skin in the vast majority of the human population. e. all bacteria that are resistant to antibiotics.

a

Which of the following is not a feature of all animals? a. defined body symmetry b. internal digestion c. motility d. cells that lack cell walls e. multicellularity

a

Which of the following is not true about Stromatolites? a. Are layered structures of Archaea b. Are layered structure of Cyanobacteria c. Were responsible for providing oxygen to a primitive earth d. Structures made of photosynthetic bacteria e. Fossilized ancient stromatolites can be found on certain parts of the world today

a

A sensitive S. aureus bacterium acquires a new gene that allows it to resist the effects of beta-lactam antibiotics (that is, the bacterium is now resistant). What might the protein encoded by that gene do? a. synthesize beta-lactam antibiotics b. digest (breakdown) beta-lactam antibiotics c. produce a toxin d. enhance colonization of human skin e. enhance entry into the bloodstream

b

Fill in the blanks with the appropriate terms. Based on observations about skin tone, scientists hypothesized that darker skin is advantageous in __________ UV environments because darker skin ___________. a. high; reduces vitamin D production b. high; protects folate from degradation c. high; increases the rate of folate synthesis d. low; allows more vitamin D to be produced e. low; allows more folate to be produced

b

When examining archaea, which of the following is not a trait that you could expect to find? a. ability to grow at high temperatures b. a nucleus c. ability to grow at extremely acidic pH d. a cell wall e. ability to survive in a high-salt environment

b

If we take the fittest bacterium from one environment—one in which the antibiotic amoxicillin is abundant, for example—and place it in an environment in which a different antibiotic is abundant, will it retain its high degree of fitness? a. yes; fitness is fitness, regardless of the environment b. yes; once a bacterium is resistant to one antibiotic it is resistant to all antibiotics c. not necessarily; fitness depends on the ability of an organism to survive and reproduce, and it may not do this as well in a different environment d. no; what is fit in one environment will never be fit in another environment

c

In humans, very-large-birth-weight babies and very tiny babies do not survive as well as midrange babies. What kind of selection is acting on human birth weight? a. directional selection b. diversifying selection c. stabilizing selection d. random selection e. steady selection

c

In the course of human evolution, which of the following environmental factors likely influenced whether a population had mostly light-skinned individuals or mostly dark-skinned individuals? a. average annual temperature b. average annual rainfall c. levels of UV light d. the vitamin D content of the typical diet e. mitochondrial DNA inheritance

c

MRSA is most likely to be problematic if found a. on the surface of the skin b. in nasal passages c. in the bloodstream d. on the fingernails e. The presence of MRSA in any of those locations indicates a serious infection

c

Organisms are placed into one or another of the three domains of life on the basis of a. cell type b. physical appearance c. evolutionary history as assessed by genetic relatedness d. ability to cause disease e. degree of sophistication, that is, how evolutionarily advanced they are

c

Our closest primate relatives, chimpanzees, have light-colored skin yet live in tropical (high-UV) environments. How would the hypothesis on the evolution of skin tone based on exposure to UV light explain this observation? a. Chimpanzees don't need folate for successful reproduction b. Chimpanzees are not susceptible to skin cancer c. The hair of chimpanzees protects their light skin from UV light d. Chimpanzees require much higher levels of vitamin D than humans do e. In chimpanzees a light-colored pigment offers UV protection

c

What are the two major mechanisms by which bacterial populations generate genetic diversity? a. mutation and meiosis b. binary fission and evolution by natural selection c. gene transfer and mutation d. mutation and binary fission e. gene transfer and replication

c

Which of the following is NOT a difference between prokaryotes and eukaryotes? a. Having a nucleus b. Having plasmid DNA in the cytoplasm c. Having ribosomes in the cytoplasm d. Having a cell wall e. Having a flagella made out of flagellin

c

A major difference between a fern and a moss is a. the presence of seeds b. the presence of flowers c. the presence of cones d. the presence of a vascular system e. the ability to carry out photosynthesis

d

Can S. aureus be present in or on a person who has no evidence of an infection? a. no; S. aureus is associated only with infections b. yes, but only non-MRSA strains are present in the absence of an infection c. yes, but only for very short periods of time (between touching a contaminated surface and washing the hands) d. yes; S. aureus is a common skin bacterium e. yes; S. aureus is a common bacterium found in the bloodstream

d

The absence of membrane-bound organelles in a cell tells you that the cell must be a. from a member of the domain Bacteria. b. from a member of the domain Archaea. c. from a member of the domain Eukarya. d. either a or b e. either b or c

d

What do mosquitos, snails, and earthworms have in common? a. They are all insects b. They are all mollusks c. They are all arthropods d. They are all invertebrates e. They all have an exoskeleton

d

What is the environmental pressure in the case of antibiotic resistance? a. the growth rate of the bacteria b. how strong or weak the bacterial cell walls are c. the relative fitness of different bacteria d. the presence or absence of antibiotics in the environment e. the temperature of the environment

d

Which of the following is not a characteristic found in at least some organisms in the domain Eukarya? a. cell walls b. photosynthesis c. multicellularity d. cells lacking a nucleus e. unicellularity

d

Which of the following would help darker-skinned people who live in low-UV environments remain healthy? a. folate supplementation b. sunscreen c. increased production of melanin d. vitamin D supplementation e. calcium supplementation

d

If you were looking for a bacterium, where would expect to find one? a. on your skin b. in soil c. in the ocean d. associated with plants e. any of the above

e

Of the following traits that are associated with being human, which evolved most recently? a. upright walking b. the ability to control fire c. social communication d. tool use e. a big brain

e

What percentage of DNA sequences do all humans share? a. 0% b. 25% c. 50% d. 75% e. >99%

e

Which of the following about Archaea is true? (from the video "Archaea" featuring Carl Woese) a. Their cells do not have a nucleus or membrane bound organelles b. They can live anywhere in the planet including extreme environments c. They have unique cell walls and produced unusual enzymes d. They have a unique genetic sequence and were only discovered in the 1970s e. All of the above

e

nuclear DNA

inherited by all children from both their mother and their father

Y-chromosome DNA

inherited only by sons from their father