Unit 2, week 2

Where in the cell is DNA found?

• Nucleus

• Golgi

• Ribosome

• Mitochondria

• Two of these

Answer explanation

The question asks about the location of DNA in the cell. The correct answer is 'Two of these'. DNA is found in both the Nucleus and the Mitochondria. The Nucleus contains the majority of the cell's genetic material, while Mitochondria have their own small amount of DNA.

In the nucleus, DNA is tightly wrapped around:

• Chromatin

• Histone

• RNA

• Euchromatin

• Two of these

The lifecycle of a cell can be divided into stages. The first 3 stages collectively make up interphase. Which of the following is NOT part of interphase?

• G1 phase

• S phase

• G2 phase

• Mitosis

• Two of these

Answer explanation

The question asks about the stages of a cell's lifecycle, specifically interphase. The interphase of a cell cycle includes G1 phase, S phase, and G2 phase. Mitosis, however, is a separate phase that comes after interphase, hence it is not part of interphase.

Which of the following does NOT correctly describes G1 of the cell cycle?

• Synthesis of new organelles and proteins.

• Cell growth

• Heterochromatin decondense

• DNA replication

• All describe G1 of the cell cycle

Answer explanation

The G1 phase of the cell cycle involves cell growth and synthesis of new organelles and proteins. However, it does not involve DNA replication. That process occurs in the subsequent S phase of the cell cycle. Thus, the statement 'DNA replication' does not correctly describe the G1 phase of the cell cycle.

S phase of the cell cycle is characterized by DNA duplication. Which of the following is NOT true of S phase of the cell cycle?

• Chromosomes are doubled

• DNA is doubled

• Each chromosome is made up of two sister chromatids

• Protein and organelle synthesis stops

• Two of these

Answer explanation

During the S phase of the cell cycle, DNA is duplicated and each chromosome is made up of two sister chromatids. However, it is not true that chromosomes are doubled. Additionally, synthesis of protein and organelles doesn't stop, they continue to be produced.

Which of the following is NOT part of prophase?

• Condensation of chromatin

• Formation of chromosomes

• Formation of an aster

• Formation of nucleus

• Migration of centrioles

Answer explanation

Prophase is the first stage of cell division. During this stage, the chromatin condenses into chromosomes, the aster forms, and centrioles migrate to opposite poles of the cell. It does not involve the formation of a nucleus. Instead, the nuclear envelope breaks down during prophase.

Which of the following phases is characterized by disjunction of the sister chromatids during mitosis?

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase

Answer explanation

Anaphase is the stage in mitosis where the sister chromatids, which were paired up during metaphase, are separated and pulled to opposite ends of the cell. This process is known as disjunction. Other phases like interphase, prophase, metaphase, and telophase do not involve the disjunction of sister chromatids.

How many pairs of homologous pairs do humans have?

• 23 pairs

• 46 pairs

• 12 pairs

• 87 pairs

• Ask Josh

Answer explanation

Humans have 23 pairs of homologous chromosomes. Homologous chromosomes are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during meiosis. These are not 46, 12, or 87 pairs. But with that said, I'd probably just ask Josh.

Which of the following does NOT occur during the G2 phase of the cell cycle?

• Cell growth

• Preparation for mitosis

• Formation of chromosomes

• All occur during the G2 phase

• Whatever Natalie picks

Answer explanation

The G2 phase is the third, final, and shortest phase in Interphase within the cell cycle in which the cell undergoes a period of rapid growth to prepare for mitosis. During this phase, cell growth and preparation for mitosis occur. However, the formation of chromosomes, which is the correct answer to this question, does not occur during this phase. Instead, chromosomes form during the prophase of mitosis.

What is the process of cell division in prokaryotes called?

• Meiosis

• Mitosis

• Binary Fission

• Cytokinesis

• Interphase

Answer explanation

The process of cell division in prokaryotes is called Binary Fission, which is a form of asexual reproduction. Unlike Meiosis and Mitosis, which are processes in eukaryotes, Binary Fission divides the cell into two equal parts. This distinguishes it from Cytokinesis and Interphase, which are stages of cell division, not the process itself.