1.
Down syndrome is a genetic disorder caused by the presence of an extra chromosome in the body cells of humans. This extra chromosome occurs in a gamete as a result of
Correct Answer
B. An error in meiotic cell division
Explanation
During meiotic cell division, the chromosomes are supposed to separate evenly, with one copy of each chromosome going to each resulting cell. However, in the case of Down syndrome, there is an error in this process, leading to the presence of an extra chromosome in the resulting cells. This error can occur during the first or second meiotic division, leading to the presence of an extra chromosome in one of the resulting gametes. When this gamete combines with another gamete during fertilization, the resulting zygote will have an extra chromosome, causing Down syndrome.
2.
Which statement best describes the relationship between cells, DNA, and proteins?
Correct Answer
B. Cells contain DNA that controls the production of proteins.
Explanation
Cells contain DNA that controls the production of proteins. This statement accurately describes the relationship between cells, DNA, and proteins. DNA is located within the cells and serves as the genetic material that carries the instructions for protein synthesis. Proteins are essential molecules that perform various functions within the cells and are synthesized based on the information encoded in the DNA. Therefore, the DNA within cells controls the production of proteins.
3.
Research has shown that certain body cells, known as stem cells, can develop into a variety of specialized cells. Various factors can cause stem cells to develop into different types of mature cells. These different types of mature cells result from
Correct Answer
C. Different environments of the cells and the functioning of different parts of the genetic
code
Explanation
The correct answer is different environments of the cells and the functioning of different parts of the genetic code. This explanation is supported by the statement in the question that various factors can cause stem cells to develop into different types of mature cells. These factors include the different environments that the cells are exposed to, as well as the functioning of different parts of the genetic code. This suggests that the development of different types of mature cells is influenced by both the external environment and the internal genetic factors within the cells.
4.
Which statement is true of both mitosis and meiosis?
Correct Answer
D. DNA replication occurs before the division of the nucleus.
Explanation
Both mitosis and meiosis involve DNA replication before the division of the nucleus. In mitosis, a single cell divides into two identical daughter cells, each with the same number of chromosomes as the parent cell. In meiosis, a single cell undergoes two rounds of division to produce four daughter cells, each with half the number of chromosomes as the parent cell. In both processes, DNA replication occurs prior to the division of the nucleus to ensure that each daughter cell receives a complete set of genetic information.
5.
A cell resulting from the fertilization of an egg begins to divide. Two cells are formed that normally remain attached and could develop into a new individual. If the two cells become separated, which statement describes what would most likely occur?
Correct Answer
A. The cells would each have all of the needed genetic information, and both could survive.
Explanation
If the two cells resulting from the fertilization of an egg become separated, they would each have all of the needed genetic information and could survive. This is because during fertilization, the egg and sperm combine their genetic material to form a complete set of chromosomes in the resulting zygote. When the zygote divides, each resulting cell would have a complete set of chromosomes, allowing them to develop into a new individual if they remain attached or survive independently if separated. Therefore, both cells would have the necessary genetic information to survive.
6.
Although all of the cells of a human develop from one fertilized egg, the human is born with
many different types of cells. Which statement best explains this observation?
Correct Answer
C. Developing cells may express different parts
of their identical genetic instructions.
Explanation
During development, cells undergo a process called differentiation where they specialize and express specific genes to perform specific functions. This allows cells with identical genetic instructions to develop into different types of cells with distinct characteristics and functions. Therefore, the statement "Developing cells may express different parts of their identical genetic instructions" best explains why a human is born with many different types of cells.
7.
Tissues develop from a zygote as a direct result of the processes of
Correct Answer
D. Mitosis and differentiation
Explanation
Tissues develop from a zygote through the processes of mitosis and differentiation. Mitosis is the process by which cells divide to produce new cells, allowing for growth and development. Differentiation is the process by which cells become specialized and take on specific functions within the body. Therefore, mitosis is responsible for the increase in cell number, while differentiation determines the specific cell types and functions within the developing tissues.
8.
Some cells involved in the process of reproduction
are represented in the diagram below.
The process of meiosis formed
Correct Answer
B. Cells 1 and 2
Explanation
The correct answer is "cells 1 and 2." This is because meiosis is a process of cell division that results in the formation of gametes (sex cells). In the diagram, cells 1 and 2 are shown, indicating that they are involved in the process of meiosis. Cell 1 is represented alone, suggesting that it is undergoing meiosis independently. Cell 2 is shown in conjunction with cell 1, indicating that they are both involved in meiosis. Cell 3 is not shown in relation to any other cell, suggesting that it is not involved in the process of meiosis.
9.
Which statement concerning the reproductive cells in the diagram below is correct?
Correct Answer
C. Each of these cells contains only half the genetic information necessary for the formation of an offspring.
Explanation
The statement that is correct is that each of these cells contains only half the genetic information necessary for the formation of an offspring. This is because the diagram represents reproductive cells, which are gametes, specifically sperm cells. Gametes are produced through a process called meiosis, which results in cells with half the number of chromosomes as the parent cells. When a sperm cell fertilizes an egg, the resulting offspring will have a combination of genetic information from both the father and the mother, resulting in genetic diversity.
10.
The development of an embryo is represented in the diagram below.
These changes in the form of the embryo are a direct result of
Correct Answer
B. Differentiation and growth
Explanation
The correct answer is differentiation and growth. The diagram represents the development of an embryo, which involves the process of differentiation, where cells become specialized and take on specific functions. Additionally, growth is also involved as the embryo increases in size and develops new structures. This is supported by the changes in form shown in the diagram, which are a result of the embryo's cells differentiating and growing.
11.
The diagram below shows a process that affects chromosomes during meiosis.
This process can be used to explain
Correct Answer
D. The origin of new combinations of traits in offspring
Explanation
The diagram shows a process that affects chromosomes during meiosis, which is the process of cell division that produces gametes (sex cells). During meiosis, homologous chromosomes exchange genetic material through a process called crossing over. This results in the creation of new combinations of traits in the offspring. Therefore, the diagram can be used to explain the origin of new combinations of traits in offspring.
12.
Which statement best explains the observation that clones produced from the same organism may not be identical?
Correct Answer
B. Gene expression can be influenced by the environment.
Explanation
Gene expression can be influenced by the environment. This means that even though clones have the same genetic information, the way their genes are expressed can be influenced by different environmental factors. These factors can include things like diet, temperature, and exposure to toxins. As a result, clones may exhibit variations in their physical traits and characteristics, despite having the same genetic makeup.
13.
The diagram below represents a nucleus containing the normal chromosome number for a species.
Which diagram bests illustrates the normal formation of a cell that contains all of the genetic information needed for growth, development, and future reproduction of this species?
Correct Answer
C. 3
Explanation
Diagram 3 best illustrates the normal formation of a cell that contains all of the genetic information needed for growth, development, and future reproduction of this species. This is because it shows a nucleus with the normal chromosome number for the species, indicating that it has the correct amount of genetic material.
14.
Which one do you like?
Correct Answer
A. Option 1