chapter 25

Question 1

how do prokaryotic and eukaryotic cells differ?

Answer 1

prokaryotes
- simple and small
- no nucleus
- no organelles
eukaryotes
- more complex and larger
- have a nucleus (chromosomes are inside)
- have organelles

Question 2

eukaryotes are defined by the presence of a nucleus more features include :

Answer 2

• a dynamic cytoskeleton
• the membrane system ( which explains their evolutionary)

Question 3

what do eukaryotic cells with dynamic features provide?

Answer 3

new possibilities for movement and feeding

Question 4

what does sexual reproduction promote?

Answer 4

it promotes genetic diversity in eukaryotic populations

Question 5

give me 2 examples how sex promotes genetic variation:

Answer 5

1. meiotic cell division results in gametes or spores
2. in fertilization, new combinations of genes are brought together by the fusion of gametes

Question 6

what’s the difference of eukaryotic life cycle between animals and plants?

Answer 6

• in animals, the zygote divides many times to form a multicellular diploid body before a small subset of cells within the body undergoes meiotic cell division to form haploid gametes (eggs and sperm).
• plants have two multicellular phases in their life cycle: haploid and diploid

Question 7

many single-celled eukaryotic organisms have evolved complex life cycles that include sexual reproduction. ”sexual reproduction” means that:
A. genetic material from two haploid cells is combined.
B. diploid cells must undergo mitotic cell division in order to reproduce.
C. haploid cells must undergo meiotic divisions to form gametes.
D. complex mating behavior likely evolved at the same time as sexual reproduction.

Answer 7

the answer is A. genetic material from two haploid cells is combined

Question 8

what does mitochondria harness to convert it to what?

Answer 8

it harness energy from organic molecules such as sugars and convert it into ATP in plant and animal cells.

Question 9

what does chloroplast capture to do what?

Answer 9

it captures the energy of sunlight to fix atmospheric carbon and synthesize simple sugars in plant cells and photosynthetic organisms.

Question 10

where did chloroplast originate from?

Answer 10

cyanobacteria, red algal chloroplasts, and plant chloroplasts ( they have similar structures and biochemical features )

Question 11

why are chloroplast genomes so small compared to cyanobacteria?

Answer 11

• the cyanobacteria most closely related to chloroplasts have thousands of genes, while the chloroplast itself has only a few hundred.
• some genes may have been lost. many other genes migrated to the nucleus of the host cell.

Question 12

which of the statements is evidence supporting the hypothesis that eukaryotic chloroplasts originated from cyanobacteria?
A. chloroplasts and cyanobacteria have similar DNA sequences for shared genes.
B. chloroplasts and cyanobacteria both have cell walls.
C. chloroplasts can leave the cell and function freely on their own.
D. chloroplasts and cyanobacteria have the same number of genes.

Answer 12

the answer is A. chloroplasts and cyanobacteria have similar DNA sequences for shared genes

Question 13

what is a proteobacteria?

Answer 13

bacteria that has similar DNA to mitochondria

Question 14

what is the main difference between the two hypotheses—endosymbiosis and infolding of the cellular membrane—for the origin of the eukaryotic cell?
A. one attributes the formation of the endoplasmic reticulum and nuclear envelope to infolding of the plasma membrane.
B. only one involves the conversion of a proteobacterium to a mitochondrion.
C. one hypothesizes that eukaryotic cells evolved from an archaeon rather than a bacterium.
D. one hypothesizes that engulfment of a proteobacterium occurred after the formation of the nuclear envelope rather than before.

Answer 14

the answer is D: the competing hypotheses differ on which membrane organelle evolved first. it is difficult to determine the origin of the nuclear envelope, so these two hypotheses continue to be a source of debate.

Question 15

what are opisthokonts?

Answer 15

the most successful group of eukaryotes including animal and fungi

Question 16

what are choanoflagellates? and what do they share in common with animals?

Answer 16

• choanoflagellates are a group of unicellular protists characterized by a ring of microvilli that forms a collar around the cell’s single flagellum.
• they share many genes, and they also share similar structures called collar cells which are found in sponges

Question 17

what member is archaeplastids?

Answer 17

members of this clade are photosynthetic, contains the green algae and the land plants

Question 18

what is the theory of endosymbiosis?

Answer 18

it suggests that mitochondria and chloroplasts were once independent prokaryotes that were engulfed by another cell.

Question 19

imagine there is a mutation in a eukaryotic cell that affects the cell’s ability to produce microtubules. Which of the answer options would you expect to be a characteristic of cells with this mutation compared to cells without the mutation?
A. ATP productions would be slower
B. productions of vesicles by the golgi would be slower
C. response rates in cell-signaling pathways would be slower
D. transport rates of mRNA out of the nucleus would be slower

Answer 19

the answer is C. since microtubules function is cell motility and determine cell shape

Question 20

green algae are most closely related to:
A. diatoms
B. red algae
C. land plants
D. brown algae

Answer 20

the answer is C. land plants

Question 21

chloroplasts are though to have evolved from:
A. cyanobacteria
B. mitochondria
C. autotrophic protists
D. proteobacteria
E. algae

Answer 21

the answer is A. cyanobacteria

Question 22

how do eukaryotic cells generate and maintain genetic diversity?
A. by allowing more mutations
B. through horizontal gene transfer
C. through asexual reproduction
D. through sexual reproduction

Answer 22

the answer is D. through sexual reproduction

Question 23

which of these features is responsible for the evolutionary success of eukaryotes?
A. having complex patterns of gene regulation
B. all of these choices are correct
C. possessing a dynamic cytoskeleton
D. possessing a dynamic endomembrane system
E. localizing where energy metabolism takes place

Answer 23

the answer is B. all choices are correct

Question 24

in animals, the egg and sperm cells are:
A. none of these are correct
B. polypoid
C. diploid
D. haploid

Answer 24

the answer is D. haploid

Question 25

mitochondria and chloroplasts are though to have arisen from:
A. none of these are correct
B. parasitic interactions
C. normal organelle development
D. endosymbiotic bacteria

Answer 25

the answer is D. endosymbiotic bacteria

Question 26

while observing a new species of seaweed under the microscope, you determine that the entire organism is one large cell containing several nuclei
A. eukaryotic
B. coenocytic
C. filamentous
D. complex multicellular
E. simple multicellular

Answer 26

the answer is B. coenocytic

Question 27

which of the options is believed to be the major event that led to the appearance of large complex animals on earth?
A. the appearance of bulk systems
B. the appearance of plants on land
C. the increase in atmospheric oxygen
D. the diversification of seaweeds in the ocean

Answer 27

the answer is C.

Question 28

in humans and many other animals, what organ system is involved in bulk transport of nutrients, oxygen, and signaling molecules?
A. circulatory system
B. digestive system
C. respiratory system
D. immune system

Answer 28

the answer is A.

Question 29

bulk flow is completely independent of diffusion; diffusion does not occur anywhere in the body of an organism that depends on bulk flow
true or false

Answer 29

false

Question 30

in what types of multicellular organisms do plasmodesmata serve as a mechanism of cell-signaling
A. plants
B. fungi
C. those types of organisms that spend only a portion of their life cycle in a multicellular state
D. animals

Answer 30

plants