1.
During which phase of mitosis do the chromosomes line up along the middle of the dividing cell?
Correct Answer
B. MetapHase
Explanation
Metaphase is the correct answer because during this phase of mitosis, the chromosomes align themselves along the middle of the dividing cell. This alignment is crucial for the equal distribution of genetic material to the resulting daughter cells. In metaphase, the spindle fibers attach to the centromeres of the chromosomes and exert tension, causing the chromosomes to line up at the metaphase plate. Once all the chromosomes are properly aligned, the cell can proceed to the next phase, anaphase, where the sister chromatids are separated and pulled towards opposite poles of the cell.
2.
The two main stages of the cell cycle are called
Correct Answer
A. Mitosis and interpHase
Explanation
Mitosis is the stage of the cell cycle where the cell divides into two identical daughter cells. During mitosis, the cell undergoes several phases including prophase, metaphase, anaphase, and telophase. Interphase is the stage between cell divisions where the cell grows, carries out its normal functions, and replicates its DNA in preparation for the next division. Therefore, mitosis and interphase are the two main stages of the cell cycle, with mitosis being the actual cell division and interphase being the period of growth and DNA replication.
3.
The first phase of mitosis is called
Correct Answer
A. PropHase
Explanation
The first phase of mitosis is called prophase. During prophase, the chromosomes condense and become visible, the nuclear membrane breaks down, and the spindle fibers begin to form. This phase marks the beginning of the process of cell division and prepares the cell for the subsequent phases of mitosis.
4.
Sea stars are genetically different from each other and from their parents. These genetic differences are the result of
Correct Answer
C. Sexual reproduction
Explanation
Sexual reproduction involves the combination of genetic material from two parents, leading to offspring that are genetically unique. This genetic variation arises from the processes of meiosis and fertilization, contributing to the differences observed among individuals.
5.
A protein called p53 can keep cells from dividing. To prevent cell division, this protein most likely stops
Correct Answer
B. Mitosis
Explanation
The protein p53 is known to inhibit cell division, which is the process of mitosis. Mitosis is the division of a cell into two identical daughter cells, and it is crucial for growth, repair, and maintenance of tissues in multicellular organisms. By stopping mitosis, p53 can effectively prevent cells from dividing and potentially regulate cell growth and development. Osmosis is the movement of water molecules across a semipermeable membrane, respiration is the process of converting glucose into energy, and mutation refers to changes in DNA sequences, none of which directly relate to cell division inhibition.
6.
When the DNA in a cell is uncoiled and spread throughout the nucleus it is called
Correct Answer
D. Chromatin
Explanation
When the DNA in a cell is uncoiled and spread throughout the nucleus, it is referred to as chromatin. Chromatin is the relaxed form of DNA that is not condensed into chromosomes. It consists of DNA strands wrapped around proteins called histones. This uncoiled structure allows for easier access to the DNA for processes such as gene expression and replication.
7.
DNA in a cell is copied during
Correct Answer
D. S pHase
Explanation
During the S phase of the cell cycle, DNA replication occurs. This is the phase where the cell's DNA is copied to produce two identical copies of the genome. The S phase is a crucial step in the cell cycle as it ensures that each daughter cell receives a complete set of genetic information. The G1 and G2 phases are involved in cell growth and preparation for DNA replication, while cytokinesis is the final stage where the cell divides into two daughter cells. Therefore, the correct answer is S phase.
8.
The spindle fibers are produced by the
Correct Answer
A. Centrioles
Explanation
Centrioles are responsible for producing spindle fibers during cell division. These spindle fibers play a crucial role in separating the chromosomes and ensuring that each daughter cell receives the correct number of chromosomes. Without centrioles, the spindle fibers would not form properly, leading to errors in chromosome distribution and potentially causing genetic abnormalities in the daughter cells. Therefore, centrioles are necessary for the proper functioning of cell division and the maintenance of genetic stability.
9.
Cleavage furrows form in which type of cells?
Correct Answer
C. Animal
Explanation
Cleavage furrows are formed during cell division in animal cells. This process, known as cytokinesis, involves the formation of a groove that deepens and eventually separates the two daughter cells. In contrast, plant cells do not form cleavage furrows but instead form a cell plate between the dividing cells. Bacteria do not have a nucleus or organelles, and their cell division process is different from that of eukaryotic cells. Therefore, the correct answer is animal cells.
10.
Cells spend most of their time in what phase?
Correct Answer
D. InterpHase
Explanation
During interphase, cells spend the majority of their time preparing for cell division. This phase involves three stages: G1, S, and G2. In G1, the cell grows and carries out its normal functions. In the S phase, DNA replication occurs, ensuring that each daughter cell will receive a complete set of genetic material. Finally, in G2, the cell continues to grow and prepares for cell division by synthesizing necessary proteins and organelles. Therefore, interphase is the phase in which cells spend the most time before entering the stages of cell division, such as prophase, cytokinesis, and mitosis.