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TLS Online TPP Program

#Question id: 1042

A student complains that it makes no sense to worry about coliform bacteria in water, since we naturally possess harmless coliforms in our intestines anyway. Why do regulatory agencies worry about coliform bacteria in water supplies, then?

#Unit 4. Cell Communication and Cell Signaling

  1. The coliforms in our intestines can sometimes turn harmful, causing intestinal infections. We need to constantly be on guard against this happening. Coliforms in water might add to this potential problem.

  2. Not all coliforms are harmless and symbiotic with human beings. Some may carry genes/proteins that can make them dangerous to humans. It's best to keep coliforms OUT of our drinking water, since it's difficult to identify which ones might be harmless and which ones might be harmful.

  3. Regulatory agencies are worried that multiple types of coliforms in water might lead to greater antibiotic resistance in the bacterial populations. They try to keep them out of water to keep antibiotic resistance levels down.

  4. Regulatory agencies simply need something to do to justify their existence. There is no real danger from coliforms in water supplies.

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TLS Online TPP Program

#Question id: 33471

#Unit 2. Cellular Organization
TLS Online TPP Program

#Question id: 33472

#Unit 2. Cellular Organization

Find correct True and False statements
A. Human females have 23 different chromosomes, whereas human males have 24.
B. In the living cell, chromatin usually adopts the extended “beads-on-astring” form.
C. The four core histones are relatively small proteins with a very high proportion of positively charged amino acids; the positive charge helps the histones bind tightly to DNA, regardless of its nucleotide sequence.
D. Nucleosomes bind DNA so tightly that they cannot move from the positions where they are first assembled.
TLS Online TPP Program

#Question id: 33473

#Unit 2. Cellular Organization

Which of the following specialized DNA sequences and their functions that act to ensure that the number and morphology of chromosomes are constant from one generation of a cell to the next.
 Replication origins B. Centromeres C. Telomeres
TLS Online TPP Program

#Question id: 33474

#Unit 2. Cellular Organization

CTG/CAG trinucleotide repeats (5ʹ- CTG in one strand and 5ʹ-CAG in the other strand) is unusually flexible. What can be their probable role?
TLS Online TPP Program

#Question id: 33475

#Unit 2. Cellular Organization

With pulsed-field gel electrophoresis, which can separate DNA molecules up to 107 bp in length. The results of pulsed-field gel electrophoresis of the DNA from the yeast Saccharomyces cerevisiae are shown in Figure. How many chromosomes does S. cerevisiae have?
TLS Online TPP Program

#Question id: 33476

#Unit 2. Cellular Organization

Find true and false statements
A. The structures of eukaryotic genes show extensive variation. 
B. Some eukaryotic genes are uninterrupted and their sequences are colinear with those of the corresponding mRNAs. 
C. Most multicellular eukaryotic genes are interrupted, but the introns vary enormously in both number and size.