1.
Which of the following is not a function of mitosis in humans?
Correct Answer
C. Production of gametes from diploid cells
Explanation
Mitosis is the process of cell division that results in the formation of two identical daughter cells. It plays a crucial role in various functions in humans, such as repair of wounds, growth, and replacement of lost or damaged cells. However, the production of gametes from diploid cells is not a function of mitosis. Gametes, such as sperm and eggs, are produced through a specialized cell division process called meiosis, which involves two rounds of division and results in the formation of haploid cells. Therefore, the correct answer is "production of gametes from diploid cells."
2.
Why is it difficult to observe individual chromosomes during interphase?
3.
A biochemist measures the amount of DNA in cells growing in the laboratory. The quantity of DNA in a cell would be found to double
Correct Answer
B. Between the G1 and G2 pHases of the cell cycle
Explanation
During the G1 phase of the cell cycle, the cell grows and prepares for DNA replication. The amount of DNA in the cell is then doubled during the S phase, where DNA synthesis occurs. After the S phase, the cell enters the G2 phase, where it continues to grow and prepare for cell division. Therefore, the quantity of DNA in a cell would be found to double between the G1 and G2 phases of the cell cycle.
4.
Which two phases of mitosis are essentially opposites in terms of changes in the nucleus?
5.
A chemical that disrupts microfilament formation would interfere with
Correct Answer
B. Formation of the mitotic spindle
Explanation
A chemical that disrupts microfilament formation would interfere with the formation of the mitotic spindle. Microfilaments are involved in the formation and organization of the mitotic spindle, which is essential for proper cell division during mitosis. The mitotic spindle is responsible for segregating the duplicated chromosomes into two daughter cells. Disrupting microfilament formation would hinder the assembly and function of the mitotic spindle, leading to errors in chromosome segregation and potentially disrupting the cell division process.
6.
If an intenstinal cell in a dog contains____chromosomes, a dog sperm cell would contain ____ chromosomes.
Correct Answer
78, 39
Explanation
Each cell in an organism contains a specific number of chromosomes, which is the genetic material that carries the organism's traits. In this case, the question states that an intestinal cell in a dog contains 78 chromosomes. During sexual reproduction, sperm cells are formed through a process called meiosis, which halves the number of chromosomes. Therefore, a dog sperm cell would contain half the number of chromosomes as the intestinal cell, which is 39 chromosomes.
7.
A micrograph of a divid cell from a mouse shows 19 chromosomes, each consisting of two sister chromatids. During which stage of meiosis couldthis picture have been taken?
8.
Tumors that remain at their site of orgin are called_____ while tumors from which cells migrate to other body tissue are called_____.
Correct Answer
benign, malignant
Explanation
Tumors that remain at their site of origin are called benign, while tumors from which cells migrate to other body tissues are called malignant. Benign tumors are usually non-cancerous and do not invade nearby tissues or spread to other parts of the body. Malignant tumors, on the other hand, are cancerous and have the ability to invade nearby tissues and spread to other parts of the body through a process called metastasis.
9.
A fruit fly somatic cell contains eight chromosomes. This means that ______ different combinations of chromosomes are possible in its gametes.
Correct Answer
16
Explanation
A fruit fly somatic cell contains eight chromosomes. During gamete formation, the chromosomes undergo a process called meiosis, which results in the formation of haploid gametes. Since the fruit fly somatic cell has eight chromosomes, each chromosome can segregate independently during meiosis. Therefore, the number of different combinations of chromosomes in its gametes can be calculated using the formula 2^n, where n is the number of chromosomes. In this case, 2^8 = 256 different combinations are possible. However, since the question asks for the number of different combinations of chromosomes, not the total number of possible gametes, the correct answer is 16.
10.
Although, nondisjunction is a random event, there are many more individuals with an extra chromosome 21, which causes Down syndrome, than individuals with an extra chromosome 2 or chromosome 16. Propose an explantion for this.