Briefly describe general trends relating to DNA content and gene number in major groups of organisms
What will be an ideal response?
Eukaryotes contain more DNA in their genomes than bacteria and exhibit a wide variation of DNA amount among different groups. Evolutionary expansion has been accompanied by increased amounts of DNA, with more "complex" forms containing more DNA than less complex forms. Such change in DNA content is not universally accompanied by increases in gene number. Some closely related species may vary more than tenfold in their DNA content.
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Injecting fibroblasts with anti-Ras antibodies that inactivate Ras proteins increases cell division
response to growth factors. __________________ Indicate whether the statement is true or false.
"Costs" associated with sexual reproduction in plants include all of the following except:a
both male and female plants or structures are required. b. death rates are high among offspring. c. gametes must come together in order for fertilization to take place. d. flowers have adapted to attract pollinators. e. offspring have a fitness equal to that of their parents.
In many parts of the Everglades in Florida, excessive irrigation is lowering water levels and allowing salt water to enter the normally freshwater swamps. Why is this a problem for plants that have adapted to life in these swamps?
A. The salt competes with minerals for uptake by the plants, limiting their growth. B. Salts bind to nitrogen, preventing it from being taken up. C. The plants cannot move sugars down the xylem if there is salt outside of the roots pulling water out. D. Photosynthesis is inhibited by salt. E. The plant roots cannot take up water if the soil salt concentration is high.
Amino acids are linked onto a polypeptide chain by ribosomes. What carries free amino acids to the ribosomes?
a. mRNA b. tRNA c. microRNAs d. rRNA e. any form of RNA