Биология для вступительных экзаменов на сестринские программы: лист заданий с ответами

What is an adaptation?

1. AA change an organism makes during its lifetime that it then passes on
2. BAn inherited trait that helps an organism survive in its environment
3. CAny mutation that damages a gene
4. DA disease that weakens a population

What does transfer RNA (tRNA) do?

1. AIt joins two DNA strands together
2. BIt copies DNA in the nucleus
3. CIt carries the code out of the nucleus
4. DIt brings amino acids to the ribosome

In genetics, what is a carrier?

1. AA person who has a dominant disorder
2. BA person with one recessive allele for a disorder but no symptoms
3. CA person who has lost both alleles for the gene, so shows no trait
4. DA person with two recessive alleles who has the disorder

Which statement about Archaea is correct?

1. AThey are prokaryotes, and many live in extreme environments
2. BThey are multicellular plants
3. CThey are a type of virus
4. DThey are eukaryotes that have a nucleus and membrane-bound organelles

There are 64 possible codons but only about 20 amino acids. What does this tell you about the genetic code?

1. AOnly 20 of the codons are ever used
2. BEach codon codes for more than one amino acid at the same time
3. CMost amino acids are coded for by more than one codon
4. DEach amino acid has exactly three codons

What does RNA polymerase do?

1. AIt builds a protein from an mRNA template
2. BIt removes introns from pre-mRNA
3. CIt copies the whole genome before cell division
4. DIt builds an RNA strand from a DNA template

Bacteria from hot springs have enzymes that work best at about 80 °C, while most human enzymes work best near 37 °C. What is the best explanation?

1. ATheir enzymes do not have an active site, so heat cannot affect them
2. BTheir enzymes have structures that stay stable at high temperatures
3. CHigh temperature never affects any enzyme
4. DTheir enzymes are made of lipids, not proteins

HIV infects and destroys helper T cells. Why do people with untreated advanced HIV get infections that healthy people rarely get?

1. AThe virus turns harmless microbes into pathogens
2. BHIV kills the normal flora of the skin and gut
3. CTheir immune response is too weak to control normally harmless microbes
4. DHelper T cells make the antibiotics that the body needs to fight infection