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Question
Why is the destruction of helper T cells caused by HIV infection so crippling to adaptive immunity?Answer
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Related questions
Q:
Glandular epithelium
Choose the one most appropriate response for each.
a. ligaments and tendons are made of this
b. contains collagen and elastin; acts as a packing material that supports internal organs
c. receives, conducts, and initiates signals in response to environmental changes
d. stores fat
e. offers resistance to mechanical injury and loss of internal fluids; also a barrier against microorganisms
f. secretes extracellular products such as sweat, mucus, tears, and saliva
g. fluid ground substance plus free cells; involved in transport, pH, and temperature stability
h. extracellular fluid that bathes cells and tissues
Q:
Which of the following is NOT found in the epidermis?
a. stratified epithelium
b. blood vessels
c. adhering cell junctions
d. keratin
e. melanin
Q:
Of the following organs, which is NOT in the abdominal cavity?
a. stomach
b. liver
c. heart
d. intestine
e. pancreas
Q:
The maintenance of the volume and composition of body fluids is the primary responsibility of which system?
a. integumentary
b. immune
c. digestive
d. urinary
e. circulatory
Q:
The endocrine system functions in
a. conduction.
b. contraction.
c. hormonal control of the body.
d. protection against disease.
e. cell production.
Q:
The following questions refer to the figure above of epithelial tissues.
This tissue is found in the gut.
a. A
b. B
c. C
d. D
e. E
Q:
The outer layer of skin is mostly ____ epithelium.
a. simple squamous
b. simple cuboidal
c. stratified squamous
d. simple columnar
e. stratified cuboidal
Q:
A tissue consists of interacting cells and
a. blood cells.
b. pigmented skin cells.
c. extracellular substances.
d. nerve cells.
e. none of these.
Q:
What happens when a plant has "foolish seedling" disease?
Q:
__________ is a response to changes in length of night relative to length of day.
Q:
In some plants, the direction of growth changes in response to contact with an object. This is called __________.
Q:
Abscission and dormancy are triggered by environmental cues such as seasonal changes in __________ or __________.
Q:
Respond to the following statements in reference to the five plant hormones listed below.
a. auxins
b. gibberellins
c. cytokinins
d. abscisic acid
e. ethylene
This hormone promotes bud and seed dormancy.
Q:
Circadian
Choose the one most appropriate answer for each. Some letters may not be used.
a. flower each successive year or after several years of vegetative growth
b. promotes cell elongation in stems
c. has receptor sites for a particular hormonal message
d. a hollow, cylindrical organ that protects young leaves growing within it
e. blue-green pigment that absorbs light energy
f. low-temperature stimulation of flowering
g. stimulates stomata closure and might be involved in root geotropism
h. stimulates fruit ripening
i. reproduces in spring
j. produces only roots, stems, and leaves the first growing season and produces flowers the second year
k. occurring on a 24-hour cycle
l. flowers in autumn
m. a nonhormonal plant growth regulator
n. lives for only one growing season
o. promotes stem elongation in plants
p. pigment involved in flowering process
Q:
Gibberellin
Choose the one most appropriate answer for each. Some letters may not be used.
a. flower each successive year or after several years of vegetative growth
b. promotes cell elongation in stems
c. has receptor sites for a particular hormonal message
d. a hollow, cylindrical organ that protects young leaves growing within it
e. blue-green pigment that absorbs light energy
f. low-temperature stimulation of flowering
g. stimulates stomata closure and might be involved in root geotropism
h. stimulates fruit ripening
i. reproduces in spring
j. produces only roots, stems, and leaves the first growing season and produces flowers the second year
k. occurring on a 24-hour cycle
l. flowers in autumn
m. a nonhormonal plant growth regulator
n. lives for only one growing season
o. promotes stem elongation in plants
p. pigment involved in flowering process
Q:
Coleoptile
Choose the one most appropriate answer for each. Some letters may not be used.
a. flower each successive year or after several years of vegetative growth
b. promotes cell elongation in stems
c. has receptor sites for a particular hormonal message
d. a hollow, cylindrical organ that protects young leaves growing within it
e. blue-green pigment that absorbs light energy
f. low-temperature stimulation of flowering
g. stimulates stomata closure and might be involved in root geotropism
h. stimulates fruit ripening
i. reproduces in spring
j. produces only roots, stems, and leaves the first growing season and produces flowers the second year
k. occurring on a 24-hour cycle
l. flowers in autumn
m. a nonhormonal plant growth regulator
n. lives for only one growing season
o. promotes stem elongation in plants
p. pigment involved in flowering process
Q:
Biennial
Choose the one most appropriate answer for each. Some letters may not be used.
a. flower each successive year or after several years of vegetative growth
b. promotes cell elongation in stems
c. has receptor sites for a particular hormonal message
d. a hollow, cylindrical organ that protects young leaves growing within it
e. blue-green pigment that absorbs light energy
f. low-temperature stimulation of flowering
g. stimulates stomata closure and might be involved in root geotropism
h. stimulates fruit ripening
i. reproduces in spring
j. produces only roots, stems, and leaves the first growing season and produces flowers the second year
k. occurring on a 24-hour cycle
l. flowers in autumn
m. a nonhormonal plant growth regulator
n. lives for only one growing season
o. promotes stem elongation in plants
p. pigment involved in flowering process
Q:
Which plant hormone listed below is responsible for the symbiotic relationship shown in the above figure?
a. auxin
b. gibberellin
c. cytokinin
d. jasmonic acid
e. abscisic acid
Q:
The requirement of cold weather before a particular plant process occurs (e.g., germination) is known as
a. the biological clock.
b. vernalization.
c. photoperiodism.
d. biennial life cycle.
e. biorhythm.
Q:
Plants cannot ____ in the dark.
a. grow
b. respire
c. move
d. utilize chlorophyll
e. sense light
Q:
Phytochrome is converted from the inactive to the active form by being exposed to light of what color?
a. far red
b. red
c. yellow
d. blue
e. none of these
Q:
The plant hormone that promotes fruit ripening is
a. auxin.
b. gibberellin.
c. cytokinin.
d. abscisic acid.
e. ethylene.
Q:
The gaseous plant hormone is
a. auxin.
b. gibberellin.
c. cytokinin.
d. abscisic acid.
e. ethylene.
Q:
The polar transport of auxin in a plant
a. creates an uneven distribution of the hormone.
b. uses active membrane transporters to move auxin in and out of cells.
c. uses membrane pumps to move hydrogen ions out of the cytoplasm into the primary cell wall.
d. activates enzymes that loosen cross-links between cellulose microfibrils.
e. does all of these.
Q:
Auxin concentration gradients
a. appear once germination begins.
b. promote the transcription of an enzyme that breaks down cytokinin.
c. allow formation of plant parts in expected patterns.
d. help young cells elongate so that shoots and roots lengthen.
e. are described by all of these EXCEPT "appear once germination begins."
Q:
Root formation in stem cuttings can be improved by the application of
a. synthetic auxins.
b. abscisic acid.
c. salicylic acid.
d. citric acid.
e. nitric acid.
Q:
Perhaps a plant's greatest liability is its inability to
a. produce growth hormones.
b. use aerobic respiration.
c. move when conditions around it deteriorate.
d. produce its own lipids and proteins.
e. respond to dwindling supplies of nutrients and water.
Q:
A pollen grain coat is composed of which of the following?
a. sporopollenin
b. cellulose
c. peptidoglycan
d. exopolysaccharides
e. none of these
Q:
Sperm nuclei are indicated by
a. A.
b. B.
c. C.
d. D.
e. E.
Q:
Meiosis is indicated by
a. A.
b. B.
c. C.
d. D.
e. E.