Question

4. In a lake governed by the food web shown in the image to the right, 500 brown trout are added from fisheries. Which of the following outcomes would most likely be expected? A. Tadpole population will increase B. Duck population will decrease C. Algae population will increase D. Lilly Pad population will decrease E. Caddis Fly larvae will increase 5. Which of the following pieces of evidence most strongly supports a common ancestor of all life on Earth? A. All organisms require energy All organisms use essentially the same genetic All organisms reproduce. All organisms show heritable variation. All organisms have undergone evolution. B. C. D. E. code 6. In the late 1950s, Meselson and Stahl many generations, then transferred them to a medium containing "N. Which of the results in the figure to the right would be expected after ONE round of DNA replication in the presence of N? a m grew bacteria in a medium containing "heavy nitrogen ("N) for A. A В.В C, C D. D E. E FN DNA A BCD. E where they are born and become 1 %-6% of the males and 0.7%-6% of the females in other populations. On an evolutionary scale, why is this significant? 7. Long-term studies of Beiding's ground squire's show that immigrants move nearly 2 kilometers from These immigrants provide a source of genetic diversity for the other populations. Those individuals that emigrate to these new populations are looking for less crowded conditions with more resources. A. B. C. Gradually, the populations of ground squirrels will move from clumped to a uniform D. These immigrants make up for the deaths of individuals, keeping the other populations population pattern of dispersion. sizes stable. In a certain mutant strain of bacteria, the enzyme leucyl-tRNA synthetase mistakenly attaches isoleucine to leucyl-tRNA 10% of the time instead of attaching leucine. These bacteria will synthesize: 8. A. proteins in which leucine is inserted at some positions normally occupied by isoleucine. B. proteins in which isoleucine is inserted at some positions normally occupied by leucine. C. no abnormal proteins, because the ribosomal translation machinery will recognize the inappropriately activated tRNAs and exclude them from the translation process. D. no proteins, because the inappropriately activated RNAs will block translation Your muscle cells, nerve cells, and skin cells have different functions because each kind of cell: 9. Bear Seal S Hvaena Cat A contains different kinds of genes. B. is located in different areas of the body. C. activates different genes. D. contains different numbers of genes. E. has experienced different mutations. of ear 14. The two strands of a DNA double helik are said to be antiparallel. What is meant by antiparallel" in this context? the term A. The twisting nature of DNA creates nonparallel strands. B. One strand runs in the 5 to 3' direction while the complementary direction. strand runs in the 3 to 5 Base pairings create unequal spacing between the two DNA strands D. One strand is positively charged and the other is negatively E. One strand contains only purines and the other contains only pyrimidines. 15. It became apparent to Watson and Crick after completion of their model that the carry a vast amount of hereditary information in which of the following? A. the sequence of bases B. the phosphate-sugar backbones C. the complementary pairing of bases D. the side groups of nitrogenous bases E. the different five-carbon sugars 16. If cytosine (C) makes up 28% of the nucleotides in a sample of DNA from an approximately what percentage of the nucleotides in this sample will be thymine (T) A. 22% B. 16% C. 44% D. 28% E. It cannot be determined from the information provided 17. In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin of replication. Which of the following would you expect as a result of this mutation? A. No proofreading will occur. B. No replication fork will be formed. C. The DNA will supercoil. D. Replication will occur via RNA polymerase alone. E. Replication will require a DNA template from another source. 18. Which enzyme catalyzes the elongation of a DNA strand in the 5- 3 direction? A. Primase B. DNA ligase C. DNA polymerase D. Topoisomerase E. Helicase 19. Which of the following help(s) to hold the DNA strands apart while they are being replicated? A. Primase B. DNA ligase C. DNA polymerase D. Single-strand Binding proteins (SSB) E. Exonuclease

Answer 1

4) The answer will be algae population will increase (Option C).

Explanation: Algae is consumed by only tadpole. On the other hand brown trout consume tadpole. So, after introducing 500 brown trout will resulted in decrease in the tadpole number. As tadpole number is decreased, algae population will be increase. So, correct answer will be option C.

5) The answer will be all organisms use essentially the same genetic code (Option B).

Explanation: Energy requirement, reproduction, heritable variation & evolution are essential for surviving in ever changing environment. It doesn't definitely tells us about the common ancestor of all life. But universality of the genetic code strongly supports that the all organism evolved from a common ancestor, as if they haven't evolved from a common ancestor then their genetic code can be different. Thus, correct answer will be option B.

6) The answer will be D (Option D).

Explanation: DNA from bacteria that grown in heavy nitrogen (¹⁵N) will give a single band at ¹⁵N. After transferring to the ¹⁴N medium due to semi-conservative replication it will give a band at ¹⁴N-¹⁵N hybrid after one round of replication. Each strand of ¹⁵N parental DNA will bind with the new ¹⁴N DNA strand that will give this hybrid band.

14) The answer will be one strand runs in the 5' to 3' direction while the complementary strand runs in the 3' to 5' direction (Option B).

Explanation: Two DNA strand are called antiparallel as they run opposite to each other, i.e., one in the 3'$\rightarrow$5' direction & another in the 5'$\rightarrow$3' direction.

16) The answer will be 22% (Option A).

Explanation: Given 28% of the nucleotides are cytosine. As cytosine binds with guanine, it will also have 28% of the nucleotides. So, (28+28)% or 56% of the nucleotides will be of guanine & cytosine. So, rest of the 44% will be adenine & thymine. So, thymine will have (44/2)% or 22% as equal amount of adenine & thymine will be present.