Unit 2 Exam

During anaphase of mitosis, what separates?

• Homologous chromosomes
• Sister chromatids
• Centromeres
• Nuclear membranes
• Spindle fibers

Answer explanation

In mitosis, sister chromatids separate; homologues do in meiosis I.

Crossing over occurs during which phase?

• Prophase I
• Metaphase I
• Anaphase I
• Prophase II
• Metaphase II

Answer explanation

Crossing over happens between homologous chromosomes in prophase I.

A homologous chromosome pair contains...

• Identical DNA sequences
• Same genes but possibly different alleles
• Random genes
• Opposite DNA strands
• Sister chromatids

Answer explanation

Homologues carry same genes but different alleles.

A homozygous genotype means...

• Same alleles
• Same genes
• Different alleles
• Same chromosomes
• None

Answer explanation

Homozygous = identical alleles for a gene.

Binary fission occurs in...

• Plant cells
• Prokaryotes
• Animal cells
• Fungi
• Gametes

Answer explanation

Prokaryotes divide by binary fission, not mitosis.

What are the three players for the initiation process of translation?

• rRNA

  amino acid

  proteins

• DNA template strand

  RNA polymerase

  Okazaki fragments

• small + large subunit

  tRNA

  mRNA strand

• anticodon

  enzyme

  codon

Answer explanation

Homologues separate, but sister chromatids stay together.

During transcription, what is produced?

• DNA copy
• mRNA
• Protein
• tRNA
• Ribosome

Answer explanation

Transcription makes mRNA from DNA.

During translation, what is assembled?

• mRNA
• Protein
• DNA
• Introns
• Spindles

Answer explanation

Translation builds protein using mRNA code.

RNA differs from DNA because RNA...

• Is double-stranded
• Has thymine
• Stays in nucleus
• Has uracil instead of thymine
• Uses deoxyribose

Answer explanation

RNA uses uracil and ribose instead of thymine and deoxyribose.

Okazaki fragments form because...

• DNA polymerase can only add to 5’ end
• DNA replicates in both directions
• Lagging strand runs opposite direction
• Helicase skips bases
• Ligase breaks bonds

Answer explanation

The lagging strand runs 3’→5’, so replication occurs in fragments later joined by ligase.