Answer: E
Difficulty: 2
Section: Genetic Information in Eukaryotes
Feedback: It is the zebrafish Danio rerio.
Answer: A
Difficulty: 2
Section: Genetic Information in Eukaryotes
Feedback: Mostly due to horizontal gene transfers, different strains of bacteria can vary wildly in their genomic sequences; however, the difference between the whole genomes of two species as distantly related as the budding yeast and the mouse is by far greater. In comparison, two human individuals differ in a few nucleotide pairs per 1000 nucleotide pairs of their genome. Genes such as ribosomal RNA genes are highly conserved and show a significant identity even between H. sapiens and E. coli.
Answer: DRDRR
Difficulty: 1
Section: The Universal Features of Cells on Earth
Feedback: Unlike DNA, cellular RNA is mainly polymerized as single-stranded molecules, allowing for folding into distinctive structures. Messenger RNAs (mRNAs) carry the information for protein synthesis. RNA contains the sugar ribose. Thymine is found in DNA.
Answer: MTTR
Difficulty: 1
Section: The Universal Features of Cells on Earth
Feedback: Ribosomal RNA forms the core of the ribosome, an RNA–protein complex. Each transfer RNA is covalently attached to a specific amino acid at one end, and displays at its other end the anticodon sequence that can pair with a codon in a messenger RNA.
Answer: OPLL
Difficulty: 1
Section: The Diversity of Genomes and the Tree of Life
Feedback: While organotrophs (such as animals) feed on organic material produced by other organisms, the primary energy converters obtain their energy from the nonliving world. Phototrophs (such as plants) use the energy of sunlight. Molecular oxygen, a by-product of phototrophs, has changed the Earth’s atmosphere and the entire biosphere. In hydrothermal vents, anaerobic lithotrophic microbes live in conditions similar to those in the early days of life on Earth.
Answer: TFFFT
Difficulty: 2
Section: The Diversity of Genomes and the Tree of Life
Feedback: We rely on plants as our source of organic carbon and nitrogen. Plants in turn rely on bacteria for organic nitrogen, but can fix carbon by themselves. Hydrothermal vents provide an example of a secluded ecosystem that lacks photosynthetic organisms.
Answer: ABE
Difficulty: 2
Section: The Diversity of Genomes and the Tree of Life
Feedback: Archaea usually live in extreme environments, and resemble eukaryotes more in their genetic machinery, and bacteria more in their metabolic machinery.
Answer: 7
Difficulty: 3
Section: Genetic Information in Eukaryotes
Feedback: The volume of the nucleus is 1000 times that of the prokaryotic cell in this example (that is, 20% × 5000), which means its diameter should be 10 times larger.
Answer: DACB
Difficulty: 3
Section: Genetic Information in Eukaryotes
Feedback: The vertebrates and insects separated about 700 million years ago. Humans and birds separated about 300 million years ago. All flowering plants share a common ancestor that lived about 150 million years ago. Humans and chimpanzees are separated by only a few million years.