Which type of bond is responsible for the unique properties of water and plays a crucial role in the structure of DNA and proteins?

A. Through electrical signals only

B. Through chemical signals only

C. Through electrical and chemical signals

D. Through mechanical signals only.

Neurons communicate with each other through both electrical and chemical signals.

The electrical signal, or action potential, runs from the cell body area to the axon terminals, through a thin fiber called axon.

Neurons also communicate with one another at junctions called synapses.

At a synapse, one neuron sends a message to a target neuron—another cell.

Most synapses are chemical; these synapses communicate using chemical messengers.

Choice A is incorrect because neurons communicate not only through electrical signals but also through chemical signals.

Choice B is incorrect because neurons communicate not only through chemical signals but also through electrical signals.

Choice D is incorrect because neurons do not communicate through mechanical signals.

A. Hydrogen bonds.

B. Covalent bonds.

C. Ionic bonds.

D. Van der Waals forces.

The correct answer is choice A. Hydrogen bonds.

Hydrogen bonds are responsible for the unique properties of water and play a crucial role in the structure of DNA and proteins.

Hydrogen bonds are weak electrostatic attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Choice B.

Covalent bonds is incorrect because covalent bonds are strong chemical bonds formed by the sharing of electrons between two atoms.

Choice C.

Ionic bonds is incorrect because ionic bonds are chemical bonds formed by the transfer of electrons from one atom to another, resulting in the formation of ions.

Choice D.

Van der Waals forces is incorrect because Van der Waals forces are weak intermolecular forces that arise from temporary dipoles induced in atoms or molecules.

A. Perforins.

B. Cytokines.

C. Granzymes.

D. Interferons.

Granzymes.

Granzymes are a family of serine proteases that are stored in and secreted from the cytotoxic granules of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells.

They work in synergy with perforin, a pore-forming toxin, to induce apoptosis in target cells.

Perforin is necessary for the delivery of granzyme B to the target cell cytosol where caspase-dependent and -independent pathways to apoptosis are activated.

Perforins (choice A) are pore-forming toxins that work in synergy with granzymes to induce apoptosis in target cells.

Cytokines (choice B) are signaling molecules that regulate immune responses but do not directly induce apoptosis in target cells.

Interferons (choice D) are a type of cytokine that play a role in immune responses but do not directly induce apoptosis in target cells.

A. Starch

B. Glycogen

C. Fructose

D. Cellulose

Glycogen is the storage form of glucose in the human body.

It is a polysaccharide that is stored primarily in the liver and muscle tissue and can be broken down into glucose when the body needs energy.

Choice A is incorrect because starch is a storage form of glucose in plants, not in the human body.

Choice C is incorrect because fructose is a simple sugar, not a storage form of glucose.

Choice D is incorrect because cellulose is a structural carbohydrate found in plant cell walls, not a storage form of glucose in the human body.

A. Enhancing the phagocytosis of pathogens and disrupting the infection

B. Attacking invading pathogens

C. Initiating cell recruitment and local inflammation

D. Secreting antibodies to neutralize pathogens .

Inflammatory cytokines released during the early response to bacterial infection play a crucial role in initiating cell recruitment and local inflammation 1.

They induce the expression of adhesion molecules in endothelial cells and promote the recruitment of neutrophils to the site of inflammation 1.

Choice A is incorrect because while inflammatory cytokines may enhance phagocytosis, they do not directly disrupt the infection.

Choice B is incorrect because inflammatory cytokines do not directly attack invading pathogens.

Choice D is incorrect because inflammatory cytokines do not secrete antibodies to neutralize pathogens.

A. Conversion to carbon monoxide.

B. Formation of carboxyhemoglobin.

C. Increased production of red blood cells.

D. Decreased pulmonary function.

Formation of carboxyhemoglobin.

Carbon monoxide binds to the hemoglobin to create a molecule called carboxyhemoglobin (COHb), which interferes with the body’s ability to transport and use oxygen, especially in the brain.

Choice A is incorrect because carbon monoxide poisoning occurs when carbon monoxide builds up in your bloodstream.

Choice C is incorrect because carbon monoxide poisoning does not increase the production of red blood cells.

Choice D is incorrect because decreased pulmonary function is not a potential complication of carbon monoxide poisoning.

A. Because water dissolves all solutes equally well.

B. Because water is a nonpolar solvent.

C. Because water is good at dissolving ions and polar molecules.

D. Because water is poor at dissolving nonpolar molecules.

Water is sometimes called the “universal solvent” because it dissolves more substances than any other liquid.

This is due to its polarity and ability to form hydrogen bonds, which allows it to dissolve ions and polar molecules.

Choice A) Because water dissolves all solutes equally well is incorrect because water does not dissolve all solutes equally well.

Choice B) Because water is a nonpolar solvent is incorrect because water is a polar solvent.

Choice D) Because water is poor at dissolving nonpolar molecules is incorrect because it does not explain why water is called the “universal solvent”.

A. Spleen

B. Kidneys

C. Pancreas

D. Thyroid gland

The correct answer is choice A.

The spleen is an organ in the human body that is responsible for the removal of damaged red blood cells and the production of certain types of white blood cells.

Choice B is incorrect because the kidneys are responsible for filtering waste from the blood and regulating electrolyte balance.

Choice C is incorrect because the pancreas produces hormones and enzymes that aid in digestion.

Choice D is incorrect because the thyroid gland produces hormones that regulate metabolism.

A. Ribosome

B. Nucleus

C. Mitochondria

D. Plasma membrane.

The plasma membrane is the organelle that encapsulates the contents of the cell and plays a vital role in regulating the movement of substances in and out of the cell.

It is a selectively permeable barrier that separates the internal environment of the cell from the external environment.

Choice A is incorrect because ribosomes are organelles involved in protein synthesis, not in regulating the movement of substances in and out of the cell.

Choice B is incorrect because the nucleus is an organelle that contains the cell’s genetic material, not in regulating the movement of substances in and out of the cell.

Choice C is incorrect because mitochondria are organelles involved in energy production, not in regulating the movement of substances in and out of the cell.

A. Progesterone

B. Testosterone

C. Estrogen

D. FSH

The correct answer is choice C. Estrogen.

Estrogen is a steroid hormone responsible for the development of female secondary sexual characteristics such as breast development, menstrual cycle, and widening of hips.

Choice A, Progesterone, is not the correct answer because it is required to maintain pregnancy and delivery.

Choice B, Testosterone, is not the correct answer because it is a hormone produced by the testes which controls the development of male secondary sexual characteristics.

Choice D, FSH (Follicle Stimulating Hormone), is not the correct answer because it stimulates the growth of ovarian follicles in females and regulates spermatogenesis in males.