Which of the following respiratory structures is affected by a disease that disrupts gas exchange, such as emphysema?

A. Skeletal muscles are not autorhythmic; this term refers to the ability to generate a rhythmical electrical impulse without the need for nervous stimulation, which is a characteristic of cardiac muscles.

B. Cardiac muscles contain intercalated discs, which are unique structural formations that allow for the rapid transmission of electrical impulses between cardiac cells. This feature is not found in skeletal muscles, which are composed of individual muscle fibers that are controlled voluntarily.

C. Cardiac muscles are involuntary, meaning they function without conscious control, which is necessary for the continuous pumping action of the heart. In contrast, skeletal muscles are under voluntary control, allowing for movement of the body in response to conscious decisions.

D. Skeletal muscles are not found in the viscera; they are attached to bones and are responsible for body movements. Cardiac muscles, on the other hand, are located in the heart, which is not in the cranium but in the thoracic cavity. The term 'viscera' refers to the internal organs in the main cavities of the body, especially those in the abdomen, not the cranium.

A. Centrosomes are the microtubule-organizing centers in cells, playing a critical role in the spatial arrangement of cell structures and in cell division.

B. Ribosomes are the molecular machines within the cell that facilitate the production of proteins by translating messenger RNA into polypeptide chains.

C. Mitochondria are known as the powerhouses of the cell, generating most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.

D. Lysosomes are membrane-bound organelles that contain enzymes capable of breaking down all types of biological polymers—proteins, nucleic acids, carbohydrates, and lipids. They are essential for intracellular digestion, the recycling of a cell's organic materials, and programmed cell death (apoptosis).

A. A gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function.

B. A locus is the specific physical location of a gene or other significant sequence on a chromosome. While a locus can contain the sequence of nucleotides that make up a gene, the term itself refers more to the position on the chromosome rather than the information for protein synthesis.

C. A promoter is a region of DNA that initiates transcription of a particular gene. Promoters are located near the transcription start sites of genes, on the same strand and upstream on the DNA. Promoters can be considered as the "on/off switch" for gene expression.

D. An operator is a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it. The operator is part of an operon model which is a system that includes the operator, the promoter, and the genes that they control.

A. Histones are proteins that provide structural support to chromosomes. They act as spools around which DNA winds, and play a role in gene regulation.

B. Chromatin is a complex of DNA and protein found in eukaryotic cells. Its primary function is packaging long DNA molecules into more compact, dense structures. This packaging allows for DNA to fit within the cell nucleus and protects DNA structure and sequence. Chromatin also plays an essential role in regulating gene expression and DNA replication. The hereditary information of humans is encoded in the DNA.

C. ATP, or adenosine triphosphate, is the energy currency of the cell. It is used to power various biochemical reactions within the cell and is not involved in storing genetic information.

D. Plasmids are small DNA molecules within a cell that are physically separated from chromosomal DNA and can replicate independently. They are most commonly found in bacteria and are not typically involved in the storage of hereditary information in humans. Plasmids are used in biotechnology to manipulate genes and are important tools in genetic engineering.

A. Water forming covalent bonds with other water molecules is a fundamental characteristic of its molecular structure, leading to the formation of a cohesive liquid that exhibits surface tension. However, this property does not directly contribute to the moderation of temperature changes.

B. Water's high specific heat capacity means it can absorb a lot of heat before it gets hot. This is why coastal areas, which are surrounded by large bodies of water, experience less dramatic temperature changes compared to inland areas. The water absorbs heat during the day, preventing temperatures from rising too quickly, and releases heat slowly at night, preventing temperatures from dropping too sharply.

C. Being a versatile solvent, water can dissolve a wide range of substances, which is crucial for many biological and chemical processes. While this property is essential for life and various ecosystems, it does not have a significant impact on the moderation of temperature changes in coastal areas.

D. Water's adhesive properties allow it to stick to other surfaces, which can slow down evaporation to some extent. However, this characteristic is more relevant to the process of water moving through materials, like plant capillaries, and does not play a major role in temperature regulation of environments.

A. A substance with a pH of 3 is not more alkaline but more acidic than a substance with a pH of 4. The pH scale measures how acidic or basic a substance is, with lower numbers being more acidic and higher numbers being more alkaline.

B. A substance with a pH of 3 is indeed 10 times more acidic than a substance with a pH of 4.

The pH scale is logarithmic, meaning each whole pH value below 7 is ten times more acidic than the next higher value.

C. A substance with a pH of 3 is not more alkaline but more acidic than a substance with a pH of 4, and the difference is not two times but ten times in terms of hydrogen ion concentration.

D. While a substance with a pH of 3 is more acidic than a substance with a pH of 4, the scale is logarithmic, so it is not simply two times more acidic, but ten times more acidic.

A. The fallopian tubes are not the source of menstrual blood and tissue. They are narrow tubes that connect the ovaries to the uterus and serve as the pathway for the egg (ovum) to travel during ovulation.

B. The uterine wall, specifically the inner lining, is the source of the blood and mucosal tissue shed during menstruation. Each month, the endometrium thickens in preparation for a potential pregnancy. If fertilization does not occur, this thickened lining is shed, resulting in menstrual bleeding.

C. The vagina, is the exit route for the menstrual flow but is not the source of the blood and tissue.

D. The ovaries, which produce eggs and hormones like estrogen and progesterone, are also not the source of menstrual blood and tissue. They are involved in the menstrual cycle by triggering the thickening of the endometrium, but the tissue itself originates from the uterine wall.

A. The rate of fall is affected by mass of the object, since object D and C fall at a faster rate than A. However it is important to consider other factors such as shape and size of the object.

B. Although objects A and B have the same mass, they do not fall at the same rate, as evidenced by their different times of fall.

C. The data does not support the conclusion that greater mass leads to a faster fall. Object C, with a mass of 30.0g, falls in 0.5sec, while object D, with a greater mass of 35.0g, falls in a longer time of 1.5sec.

D. A and B have the same mass but have different rates of fall. This indicates that air resistance is greater for A, hence the slower rate of fall.

A. The browning of an apple slice is caused by the enzyme polyphenol oxidase, which is present in the apple, not the lemon juice.

B. This acidic environment can denature the polyphenol oxidase enzyme in the apple, rendering it inactive and thus preventing the browning reaction.

C. The browning is a result of a chemical reaction, and dilution would not prevent the reaction from occurring.

D. The browning is due to the formation of melanin, which are pigments resulting from the enzymatic reaction. Lemon juice's acidity affects the enzyme responsible for this reaction, not the pigments themselves.

A. Both endocrine and exocrine glands produce secretions that affect target cells, but the way they deliver these secretions to the target cells is different. Endocrine glands release hormones directly into the bloodstream, which then travel to the target cells, while exocrine glands secrete their products into ducts that lead directly to the target areas.

B. Nerve innervation refers to the supply of nerves to a particular part of the body or organ.

While nerve innervation can influence the activity of glands, it is not the primary distinguishing feature between endocrine and exocrine glands.

C. The biochemical nature of the secretions can vary widely among different glands, but this is not the main characteristic that differentiates endocrine from exocrine glands. Both can produce a variety of biochemical substances, including enzymes, hormones, and other compounds.

D. This is the key difference between endocrine and exocrine glands. Endocrine glands are ductless and release their hormones directly into the bloodstream, allowing them to be transported throughout the body. In contrast, exocrine glands have ducts through which they release their secretions to the surface of an organ or tissue, or to the outside of the body.