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Question
When Pasteur tested the hypothesis of spontaneous generation, he compared the ability of a sterilized growth medium (meat broth) to produce a population of bacteria in two different types of flasks. One had a simple neck open to the outside, and the other had a "goose neck" bend that also was open to the environment. Pasteur expected that bacteria would appear in the flask with the standard neck. In this experiment, the standard neck flask served as a/an:
A) observation.
B) variable.
C) control.
D) statistic.
E) hypothesis.
Answer
This answer is hidden. It contains 1 characters.
Related questions
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As sperm are made, they travel through the vas deferens and are stored in the seminal vesicles until ejaculation.
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Which of the following best describes the period during which the developing offspring is considered a fetus?
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B) from fertilization to eight weeks
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D) the third trimester only
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Which of the following statements concerning sperm and fertilization is correct?
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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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Sperm development takes about:
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B) 28 days.
C) 6 months.
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The sequence of development of sperm is:
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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
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On average, about how often does ovulation occur?
A) every 6 months
B) every 28 days
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Through what structure does an oocyte travel on its way to the uterus?
A) uterine tube
B) cervix
C) vagina
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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 ________.
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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?
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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.
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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.
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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
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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.
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Of the choices listed, the first event that occurs during embryonic development is:
A) germ layer formation.
B) blastula formation.
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Which characteristic is typical of the vegetal pole of an embryo?
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B) The vegetal pole is always hollow.
C) The vegetal pole contains relatively less yolk.
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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:
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B) gastrulation.
C) organogenesis.
D) fertilization.
E) induction.