Nokea
What controls muscles by sending electrical impulses to the muscles?
- A. Blood vessels
- B. Nerves
- C. Hormones
- D. Neurons
Correct Answer: B
Rationale: Nerves control muscles by transmitting electrical impulses that initiate muscle contractions. Blood vessels are responsible for transporting blood, not controlling muscles. Hormones are chemical messengers produced by glands to regulate bodily functions, not specifically controlling muscles. Neurons are the basic building blocks of the nervous system that transmit signals, but nerves are the specific structures that control muscles by sending electrical impulses.
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Where does the digestion of food start?
- A. Esophagus
- B. Stomach
- C. Small intestine
- D. Mouth
Correct Answer: D
Rationale: The correct answer is the mouth. Digestion begins in the mouth where mechanical breakdown occurs through chewing, and chemical breakdown begins with saliva. Enzymes in saliva start breaking down carbohydrates, initiating the digestion process. The esophagus is responsible for transporting food from the mouth to the stomach and does not play a role in the digestion process. The stomach continues the digestion process after the food leaves the mouth. The small intestine is primarily responsible for absorbing nutrients from the digested food, rather than being the initial site of digestion.
What is apoptosis, and how is it involved in embryonic development?
- A. Uncontrolled cell growth
- B. Programmed cell death
- C. DNA replication
- D. Cell division
Correct Answer: B
Rationale: Apoptosis is the process of programmed cell death, not uncontrolled cell growth (Choice A). It plays a vital role in embryonic development by eliminating unnecessary or damaged cells, sculpting organs, and ensuring proper tissue organization. Through apoptosis, the embryo undergoes controlled cell death to shape structures accurately. This mechanism is essential for the precise development of organs and tissues, emphasizing the significance of apoptosis in embryogenesis. DNA replication (Choice C) and cell division (Choice D) are essential cellular processes but are not directly related to apoptosis or its role in embryonic development.
What is an electrically charged atom called?
- A. Ion
- B. Isotope
- C. Molecule
- D. Compound
Correct Answer: A
Rationale: An ion is an atom that has gained or lost electrons, resulting in a positive or negative charge, making it electrically charged. This term specifically refers to atoms with a net electrical charge. Isotopes are atoms of the same element with different numbers of neutrons, not electrically charged. Molecules are formed when atoms bond together, but they are not necessarily charged. Compounds are substances composed of different elements bonded together, but they may not be electrically charged.
Which of the following types of stem cells can differentiate into any cell type, including forming an entire organism?
- A. Totipotent stem cells
- B. Multipotent stem cells
- C. Pluripotent stem cells
- D. Hematopoietic stem cells
Correct Answer: A
Rationale: Totipotent stem cells possess the unique ability to differentiate into any cell type, including forming an entire organism. These cells have the highest potency level and can give rise to both embryonic and extraembryonic cell types, allowing them to develop into a complete organism. Multipotent stem cells (Choice B) can differentiate into a limited range of cell types within a specific tissue or organ. Pluripotent stem cells (Choice C) can differentiate into any cell type in the body except for those needed to support and develop a fetus. Hematopoietic stem cells (Choice D) are a type of multipotent stem cell that can differentiate into various blood cell types.
How many grams of solid CaCO3 are needed to make 600 mL of a 35 M solution? The atomic masses for the elements are as follows: Ca = 40.1 g/mol; C = 12.01 g/mol; O = 16.00 g/mol.
- A. 18.3 g
- B. 19.7 g
- C. 21.0 g
- D. 24.2 g
Correct Answer: B
Rationale: 1. First, calculate the molar mass of CaCO3 by adding the atomic masses of Ca, C, and 3 O atoms: 40.1 + 12.01 + (3 * 16.00) = 100.13 g/mol.
2. Calculate the number of moles in 600 mL of a 35 M solution: 600 mL * 35 mol/L = 21,000 mmol.
3. Convert moles to grams using the molar mass of CaCO3: 21,000 mmol * (100.13 g/mol / 1000 mmol/mol) = 2,102.73 g.
4. Therefore, you would need 19.7 g of solid CaCO3 to make 600 mL of a 35 M solution.