Nokea
What happens during a physical change in matter?
- A. A new substance with different properties is formed
- B. The chemical composition of the substance changes
- C. The original substance can be recovered by physical means
- D. Energy is either released or absorbed
Correct Answer: C
Rationale: During a physical change in matter, the original substance undergoes a change in its physical state or appearance without any change in its chemical composition. This means that the original substance can be recovered by physical means, such as melting, freezing, boiling, or condensing. No new substance is formed (option A), the chemical composition remains the same (option B), and energy changes can occur but are not a defining characteristic of a physical change (option D). The ability to recover the original substance by physical means distinguishes physical changes from chemical changes.
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What is the process of transporting molecules across the cell membrane against a concentration gradient called?
- A. Diffusion
- B. Osmosis
- C. Active transport
- D. Facilitated diffusion
Correct Answer: C
Rationale: A) Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration, which does not require energy input.
B) Osmosis is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
C) Active transport is the process of transporting molecules across the cell membrane against a concentration gradient, requiring energy in the form of ATP to move substances from an area of lower concentration to an area of higher concentration.
D) Facilitated diffusion is a type of passive transport that involves the use of transport proteins to move molecules across the cell membrane from an area of higher concentration to an area of lower concentration, without the need for energy input.
Which of the following is the outermost layer of the skin, providing protection against pathogens and the environment?
- A. Dermis
- B. Epidermis
- C. Hypodermis
- D. Stratum corneum (part of the epidermis)
Correct Answer: B
Rationale: The epidermis is the correct answer as it is the outermost layer of the skin, providing protection against pathogens and the environment. It consists of multiple layers, including the stratum corneum, which is the outermost layer of the epidermis. The dermis is located beneath the epidermis, offering structural support and housing blood vessels, nerves, and glands. The hypodermis is the deepest layer of the skin, made up of fat and connective tissue that secures the skin to underlying structures. Choice A, Dermis, is incorrect as it is located beneath the epidermis. Choice C, Hypodermis, is incorrect as it is the deepest layer of the skin, not the outermost. Choice D, Stratum corneum (part of the epidermis), is not the correct answer as it is a specific layer within the epidermis and not the overall outermost layer of the skin.
What is the term for the process of a gas changing directly into a solid?
- A. Condensation
- B. Deposition
- C. Sublimation
- D. Evaporation
Correct Answer: B
Rationale: The correct term for the process of a gas changing directly into a solid is deposition. During deposition, gas particles lose energy and transition directly into the solid state without passing through the liquid phase. Sublimation, on the other hand, is the process in which a solid changes directly into a gas without going through the liquid phase. Condensation is the process where gas changes into a liquid state. Evaporation, on the contrary, is the conversion of a liquid to a gas. Therefore, the correct answer is B, deposition.
During which stage of meiosis II are sister chromatids separated, resulting in four genetically unique daughter cells?
- A. Prophase I
- B. Prophase II
- C. Anaphase I
- D. Anaphase II
Correct Answer: D
Rationale: - Prophase I occurs in meiosis I, not meiosis II. During Prophase I, homologous chromosomes pair up and exchange genetic material in a process called crossing over.
- Prophase II is the stage where the nuclear envelope breaks down, and spindle fibers start to reappear, preparing the cell for division. Sister chromatids are still attached during Prophase II.
- Anaphase I is the stage in meiosis I where homologous chromosomes are separated and pulled to opposite poles of the cell.
- Anaphase II is the stage in meiosis II where sister chromatids are separated and pulled to opposite poles of the cell, resulting in four genetically unique daughter cells. This is the stage where the final separation of genetic material occurs, leading to the formation of haploid daughter cells.
What element is responsible for the green color of leaves?
- A. Magnesium
- B. Iron
- C. Copper
- D. Zinc
Correct Answer: A
Rationale: Magnesium is the correct answer. It is essential for the formation of chlorophyll, the green pigment in plants that is crucial for photosynthesis. Chlorophyll absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose and oxygen. Iron, copper, and zinc do not play a direct role in the green color of leaves. Iron is more related to processes like electron transport, copper is involved in enzyme functions, and zinc contributes to the synthesis of plant growth regulators.