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What happens when an atom loses an electron?
- A. It forms a molecule.
- B. It gains a positive charge and becomes an ion.
- C. It alters its elemental identity.
- D. No change occurs; it remains neutral.
Correct Answer: B
Rationale: When an atom loses an electron, it gains a positive charge and becomes an ion. This occurs because the number of protons in the atom exceeds the number of electrons, leading to a positive charge. Therefore, the atom undergoes a transformation into an ion by losing an electron. Choice A is incorrect because losing an electron does not result in the formation of a molecule, as molecules are made up of bonded atoms. Choice C is incorrect because losing an electron does not change the fundamental identity of the atom; it only changes its charge. Choice D is incorrect because losing an electron causes the atom to become positively charged, altering its neutrality.
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What is the significance of studying pedigrees in human genetics?
- A. Predicting the exact outcome of genetic crosses in humans.
- B. Tracing the inheritance of complex traits with multiple contributing genes.
- C. Identifying carriers of dominant genetic disorders.
- D. Determining the risk of acquiring a specific mutation de novo.
Correct Answer: B
Rationale: Pedigrees are diagrams that show the relationships within a family and can be used to track the inheritance patterns of specific traits or diseases. While pedigrees can provide information on the inheritance of single gene disorders (such as identifying carriers of dominant genetic disorders, as mentioned in option C), their primary significance lies in studying complex traits with multiple contributing genes. These traits do not follow simple Mendelian inheritance patterns and are influenced by both genetic and environmental factors. By analyzing pedigrees, researchers can identify patterns of inheritance for complex traits, such as polygenic diseases or traits influenced by gene-environment interactions. Therefore, option B is the most appropriate choice as it captures the main significance of studying pedigrees in human genetics.
What is the term for a group of organisms living in the same place and interacting with each other?
- A. Ecosystem
- B. Community
- C. Population
- D. Niche
Correct Answer: B
Rationale: - A) Ecosystem refers to a biological community of interacting organisms and their physical environment.
- B) Community specifically refers to a group of organisms of different species living in the same place and interacting with each other.
- C) Population refers to a group of individuals of the same species living in the same area.
- D) Niche refers to the role or function of an organism or species within an ecosystem.
In this context, the term for a group of organisms living in the same place and interacting with each other is best described as a community because it involves multiple species interacting within a shared habitat.
What are the two main divisions of the skeletal system?
- A. Upper and lower body bones
- B. Axial and appendicular skeleton
- C. Long and short bones
- D. Compact and spongy bone
Correct Answer: B
Rationale: The skeletal system is divided into two main divisions: the axial skeleton and the appendicular skeleton. The axial skeleton comprises the skull, vertebral column, and rib cage, providing structural support and protection for vital organs. On the other hand, the appendicular skeleton includes the bones of the upper and lower limbs, shoulder girdle, and pelvic girdle, facilitating movement and flexibility. The divisions are based on the location and function of the bones within the skeletal system, making choices A, C, and D incorrect as they do not represent the primary divisions of the skeletal system.
Where does fertilization, the fusion of sperm and egg, typically occur in the human body?
- A. Ovary
- B. Uterus
- C. Fallopian tube
- D. Vagina
Correct Answer: C
Rationale: Fertilization typically occurs in the fallopian tube. This is where the sperm and egg meet and fuse to form a zygote. The fallopian tube provides the optimal environment for fertilization as it helps in the transportation of the egg and provides a suitable site for fertilization before the resulting embryo travels to the uterus for implantation. Choices A, B, and D are incorrect. The ovary is where eggs are produced, the uterus is where the fertilized egg implants and develops into a fetus, and the vagina is the canal that leads to the cervix, but fertilization itself does not occur in these locations.
Which hormone, produced by the ovaries, is responsible for the development of the uterine lining during the menstrual cycle and supports early pregnancy?
- A. Estrogen
- B. Progesterone
- C. Testosterone
- D. Prolactin
Correct Answer: B
Rationale: Progesterone, produced by the ovaries, is responsible for the development of the uterine lining during the menstrual cycle and supports early pregnancy. While estrogen also plays a crucial role in the menstrual cycle, progesterone is specifically known for its role in preparing the uterus for pregnancy and maintaining the uterine lining. Testosterone is primarily a male sex hormone and not directly involved in these processes. Prolactin is a hormone that is mainly associated with milk production and not related to the development of the uterine lining or early pregnancy.