Nokea
Why does cytokinesis occur?
- A. To duplicate DNA
- B. To convert energy within organelles
- C. To eliminate bacteria
- D. To divide daughter cells
Correct Answer: D
Rationale: Cytokinesis is the process of cell division following mitosis, where the cytoplasm of a cell is split into two daughter cells. The main purpose of cytokinesis is to physically separate the newly formed nuclei and organelles into individual cells, ensuring that each daughter cell receives a complete set of cellular components to function independently. Therefore, the correct answer is D, as the primary outcome of cytokinesis is the division of daughter cells.
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What organisms cannot produce energy without oxygen?
- A. Obligate anaerobes.
- B. Strict aerobes.
- C. Facultative aerobes.
- D. Facultative anaerobes.
Correct Answer: B
Rationale: Correct Answer: B - Strict aerobes
Rationale:
1. Strict aerobes require oxygen for energy production through aerobic respiration.
2. Without oxygen, strict aerobes cannot generate energy efficiently.
3. Obligate anaerobes (A) do not require oxygen and can produce energy through anaerobic respiration.
4. Facultative aerobes (C) can switch between aerobic and anaerobic respiration based on oxygen availability.
5. Facultative anaerobes (D) can generate energy through both aerobic and anaerobic respiration, depending on the environment.
Summary:
Strict aerobes are organisms that solely rely on oxygen for energy production. Other choices (A, C, D) can adapt their energy production methods based on oxygen availability.
In the human life cycle, only sperm and eggs have which number of chromosomes?
- A. Diploid
- B. Polyploid
- C. Monoploid
- D. Haploid
Correct Answer: D
Rationale: In humans, sperm and egg cells are haploid, meaning they contain half the number of chromosomes (23) compared to diploid cells (46). This reduction in chromosome number is essential for sexual reproduction, allowing the formation of a diploid zygote upon fertilization. Haploid cells carry only one set of chromosomes, which is necessary for genetic diversity and the fusion of genetic material during fertilization.
What type of bond connects sugar and phosphate in DNA?
- A. hydrogen
- B. ionic
- C. covalent
- D. overt
Correct Answer: C
Rationale: The correct answer is covalent (Choice C). In DNA, the bond connecting the sugar and phosphate groups is a phosphodiester bond, which is a type of covalent bond. Covalent bonds involve the sharing of electrons between atoms, forming strong and stable connections. Hydrogen bonds are important in DNA structure but are not the primary bond connecting sugar and phosphate. Ionic bonds involve the transfer of electrons between atoms, which is not the case in sugar-phosphate bonds. 'Overt' is not a term used to describe the bond between sugar and phosphate in DNA.
Are all bacteria bad, and do they always cause infections?
- A. TRUE
- B. FALSE
- C. Sometimes
- D. Not sure
Correct Answer: B
Rationale: The misconception that all bacteria are harmful and always cause infections is incorrect. Although some bacteria can lead to diseases, it is essential to note that not all bacteria are harmful. In reality, certain bacteria are beneficial and serve important functions in the body, such as aiding in digestion. Therefore, the correct answer is FALSE.
How is the aerodynamic nature of a bird's wing best categorized in biology?
- A. Organisms and their environment
- B. Ontogeny
- C. Structure and function
- D. Heredity
Correct Answer: C
Rationale: The aerodynamic nature of a bird's wing exemplifies the relationship between its structure and its function, showcasing how its form is intricately adapted for its function of flight. This concept of the interdependence of structure and function is a fundamental theme in biology. It emphasizes how the structures of living organisms are precisely designed to carry out specific functions, thereby influencing their survival and success in their respective environments.