Clones of B or T cells are:
a. being produced continually
b. interchangeable
c. produced only when their surface receptors recognize a specific antigen
d. involved in innate immunity
e. produced and mature in the bone marrow
c
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In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____
A) ATP, CO2, and ethanol (ethyl alcohol) B) ATP, CO2, and lactate C) ATP, NADH, and pyruvate D) ATP, pyruvate, and acetyl CoA
In a negative feedback mechanism, the response directs the system to operate in a similar direction. For example, if an individual is cold, the negative feedback mechanism would direct the body to become colder.
Indicate whether the statement is true or false.
Would there be a cost of sex if sexual reproduction was isogamous?
a. No, females would not pay the twofold cost of sex. b. Yes, sex may break up coadapted gene complexes. c. No, females would still transmit the same proportion of their genes to the next generation. d. Yes, despite contributing the same proportion of offspring as asexual fe-males, isogamous sexual females would only transmit half the proportion of their genes to the next generation.
Which of the following statements about non-coding DNA is TRUE?
The role of non-coding DNA is understood to be extra genes that only get turned on in situations where the regular genes become damaged. Non-coding DNA can only occur between genes, not within genes themselves. "Junk DNA" refers to the proportion of base sequences in DNA that do not code for anything and seem to have no obvious purpose. Bacteria have the most non-coding DNA; more than 90% of their genome contains introns. Fruit flies are one of few organisms to have less coding DNA than humans.