Escherichia coli is plated on nutrient agar plates that each contain a different type of antibiotic. The shaded area represents growth of the bacteria. Which of the following plates contains bacteria that were most resistant to the antibiotic?

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. Plasma cells are specialized white blood cells that produce antibodies, which are proteins that can bind to and help neutralize pathogens like bacteria and viruses.

B. Helper T-cells play a crucial role in the immune system by activating and directing other immune cells, including B-cells to produce antibodies and cytotoxic T-cells to kill infected cells. They recognize foreign antigens presented by antigen-presenting cells and release cytokines that stimulate the immune response.

C. Cytotoxic T-cells, also known as killer T-cells, directly attack and destroy cells that have been infected by viruses or have become cancerous. They are part of the adaptive immune response and are important for eliminating intracellular pathogens.

D. Natural killer cells are a type of lymphocyte that can kill virus-infected cells and tumor cells without prior sensitization to them. They are part of the innate immune system and provide a rapid response to virally infected cells and a degree of immune memory.

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 kidneys are a pair of bean-shaped organs located in the posterior part of the abdomen.

They are primarily responsible for filtering blood, removing waste products, and excess substances through the urine. The kidneys maintain overall fluid balance, regulate and filter minerals from blood, and create hormones that help produce red blood cells, promote bone health, and regulate blood pressure.

B. The liver, while it does process nitrogenous waste, its primary role is to detoxify chemicals and metabolize drugs. The liver secretes bile that ends up back in the intestines and also makes proteins important for blood clotting and other functions.

C. The gallbladder stores and concentrates bile produced by the liver, releasing it into the small intestine to aid in the digestion of fats. It does not remove nitrogenous waste from the body.

D. The large intestine absorbs water and salts from the material that has not been digested as food, and is passed from the small intestine. It also stores waste products until they're excreted. It is not directly involved in the removal of nitrogenous waste.

A. A centrifuge is a device that separates components in a liquid by spinning at high speed, which forces heavier materials to the outer edge of the spinning container. It is not typically used to measure turbidity.

B. A spectrophotometer is an instrument that measures the amount of light that passes through a sample. It is commonly used to measure turbidity because it can quantify how much light is absorbed by suspended particles in the liquid.

C. A microdensitometer is used to measure the density of microscopic particles on photographic or radiographic film, which is not directly related to the measurement of turbidity in a liquid.

D. An electrophorometer is an instrument used to measure the rate of movement of charged particles in a fluid under the influence of an electric field. It does not measure turbidity or the transmission of light through a sample.

A. A pivot joint allows for rotational movement around a single axis. An example of a pivot joint is the atlantoaxial joint in the neck, which allows for the rotation of the head.

B. A hinge joint permits movement in one plane, much like the opening and closing of a door.

C. The elbow and knee joints are classic examples of hinge joints, allowing for flexion and extension.

D. Gliding joints, also known as plane joints, allow for sliding movements in multiple directions within a plane. These are found in areas like the carpals of the wrist, where small bones slide against each other to allow for a range of movements.

The hip joint is a ball-and-socket joint, which is characterized by a spherical end of one bone fitting into a cup-like depression of another bone. This structure allows for a wide range of motion, including flexion, extension, abduction, adduction, and rotation. The hip joint, specifically, is formed by the articulation of the head of the femur and the acetabulum of the pelvis. It is designed for stability and weight-bearing, making it one of the most stable joints in the human body. This type of joint is also found in the shoulder, where the humerus fits into the glenoid fossa of the scapula.

A. Urea is a waste product formed in the liver through the metabolic breakdown of proteins and is excreted by the sweat glands. When proteins are broken down, ammonia is formed, which is toxic to the body. The liver converts ammonia into urea, which is less toxic and can be safely transported in the bloodstream to be eliminated through sweat and urine.

B. Lysozymes are enzymes that are part of the immune system and are found in various body fluids, including sweat. However, they are not specifically related to the breakdown of proteins and the formation of ammonia.

C. Sebum is an oily substance produced by sebaceous glands, not sweat glands. It helps to lubricate and protect the skin but is not involved in the excretion of waste products from protein metabolism.

D. Water is a major component of sweat and is excreted by sweat glands to help regulate body temperature through evaporative cooling. While it is a component of sweat, it is not specifically excreted in response to protein breakdown and ammonia formation.

A. The renal vein is the vessel that drains oxygen-depleted blood away from the kidneys. It connects the kidneys to the inferior vena cava, which then carries the blood back to the heart to be re-oxygenated.

B. The renal artery is responsible for delivering oxygen-rich blood from the heart to the kidneys. It branches off from the abdominal aorta and enters the kidneys to supply them with the necessary oxygen and nutrients.

C. The urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of fluids from the body. It is not involved in the drainage of blood from the kidneys.

D. The ureter is a duct that allows the passage of urine from the kidneys to the urinary bladder. Similar to the urethra, it does not carry blood but is part of the urinary system to excrete urine.

A. Proton pumps are transport proteins that move protons (hydrogen ions) across a biological membrane against their concentration gradient, using energy from ATP. They are not primarily involved in the movement of water molecules.

B. Electrochemical gradients involve the movement of charged particles across a membrane due to a difference in concentration and charge. While they can influence the movement of water indirectly, they are not the main mechanism for water transport.

C. Facilitated diffusion is the process by which substances, including water, move down their concentration gradient across a cell membrane with the help of carrier proteins. In the case of water, this process is specifically called osmosis.

D. Gated channels are types of protein channels that open or close in response to certain stimuli to allow the passage of specific ions or molecules. While they can transport water in certain circumstances, they are not the primary route for water entering cells.

A. The alveoli are the tiny air sacs within the lungs where the exchange of oxygen and carbon dioxide takes place. In diseases like emphysema, the walls between the alveoli can be damaged, leading to fewer and larger air sacs instead of many tiny ones. This reduces the surface area for gas exchange, making it difficult for the body to get the oxygen it needs.

B. The trachea, or windpipe, is the main airway that leads to the lungs. While it is not directly involved in the gas exchange process, it does play a crucial role in providing a clear path for air to reach the respiratory structures deeper within the lungs.

C. The primary bronchi are the two main branches from the trachea that lead into each lung.

They are large airways that begin the process of directing air to the lungs' smaller passages but are not the sites of gas exchange.

D. The secondary bronchi, also known as lobar bronchi, are divisions of the primary bronchi that enter each lobe of the lungs. Like the primary bronchi, they are part of the airway system that conducts air to and from the gas exchange surfaces but are not themselves involved in the exchange of gases.