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Question
Diffusing molecules move ________ until they are ________.
A) down their concentration gradients; evenly distributed
B) up their concentration gradients; evenly distributed
C) through channels of active transport proteins; evenly distributed
D) up their concentration gradients; unevenly distributed
E) down their concentration gradients; unevenly distributed
Answer
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Related questions
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Which of the following best describes the period during which the developing offspring is considered a fetus?
A) from fertilization to three weeks
B) from fertilization to eight weeks
C) the first trimester only
D) the third trimester only
E) from nine weeks until birth
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An ectopic pregnancy is:
A) implantation of the embryo in the uterus.
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Which of the following statements concerning sperm and fertilization is correct?
A) The first sperm that approaches the egg is the one to fertilize the egg.
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C) The first capacitated sperm fertilizes the egg.
D) Several sperm must contribute their DNA to the egg for fertilization to occur.
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A man has been experiencing reduced urine flow problems. After examination by his doctor, the diagnosis is an enlarged prostate gland. What is the connection between prostate enlargement and reduced urine flow?
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Sperm development takes about:
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B) 28 days.
C) 6 months.
D) 2.5 months.
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The sequence of development of sperm is:
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B) primary spermatocyte, spermatogonia, sperm.
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D) spermatogonia, spermatocyte, spermatid, sperm.
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The vas deferens ducts empty sperm into the:
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Which structure would be best described as helping to prepare the female tract for pregnancy and maintain it during the early phases of pregnancy?
A) vagina
B) uterine tube
C) oocyte
D) corpus luteum
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On average, about how often does ovulation occur?
A) every 6 months
B) every 28 days
C) every 14 days
D) every day
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Through what structure does an oocyte travel on its way to the uterus?
A) uterine tube
B) cervix
C) vagina
D) ovary
Q:
If you could stop diffusion of substances in fruit fly zygotes, could you stop normal development? Why or why not?
Q:
Programmed cell death is also known as ________.
Q:
You are a substitute teacher in a high school biology lab class on the day the students are dissecting frogs. A particularly bright student happens to notice that the left adrenal gland is malformed in her frog. She asks if a problem in embryonic development could have caused that. Although there may be more than one reason, what might you propose as an explanation based on embryonic development?
Q:
Match the following. Answers may be used more than once.A) cleavageB) organogenesisC) gastrulationNeural tube forms
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Different cell layers may have different cell adhesion molecules.
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Cells become more and more specialized as development progresses.
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Eye cells can become beak cells once they are committed.
Q:
Bicoid is only one type of morphogen.
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Cleavage and gastrulation take place in animals such as humans and birds but not in frogs.
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The blastula is the stage of embryonic development in which cells migrate.
Q:
The end of a zygote that contains less yolk is the animal pole.
Q:
ZPA cells of the chick embryo produce which morphogen?
A) sonic hedgehog
B) sonic chicken
C) bicoid
D) chicken wing factor
Q:
Which of the following is a process by which an initial set of genes turns on a second set of regulatory genes, which eventually turns on a third set of genes?
A) developmental chain reaction
B) gastrulation
C) the sonic hedgehog sequence
D) the genetic cascade
E) somite production
Q:
What is the effect of higher concentration of bicoid protein in part of a fruit fly embryo?
A) It will develop into the posterior end of the organism.
B) It will develop into the heart of the organism.
C) It will develop into the head end of the organism.
D) It lowers the chances of embryo survival.
Q:
Of the choices listed, the first event that occurs during embryonic development is:
A) germ layer formation.
B) blastula formation.
C) organogenesis.
D) cleavage.
Q:
Which characteristic is typical of the vegetal pole of an embryo?
A) The vegetal pole is composed of a single, large cell.
B) The vegetal pole is always hollow.
C) The vegetal pole contains relatively less yolk.
D) The vegetal pole has a relatively greater proportion of yolk.
E) The vegetal pole is the site of the development of the mouth.
Q:
The phase during which embryonic cells arrange themselves into three layers is called:
A) cleavage.
B) gastrulation.
C) organogenesis.
D) fertilization.
E) induction.