The covalent bonds between the monomers of an enzyme macromolecule are:

Given the new findings that worm infestation can relieve the effects of certain autoimmune disorders, the hypothesis should be modified to state that worm infestation reduces the severity of certain autoimmune disorders.

This option best reflects the new information and suggests a potential benefit of worm infestation in relation to autoimmune disorders. The other options do not accurately reflect the new findings and do not provide a clear modification to the hypothesis.

The best reason for the prolonged preservation of the body is that it was frozen in the cold temperature of the Alps shortly after death and remained frozen until it was found. Freezing can preserve a body by slowing down or stopping the decomposition process.

The other options are not as likely to have caused prolonged preservation.

Ultraviolet rays can damage molecules rather than preserve them. Toxins in food would not necessarily kill all bacteria that could cause decomposition. Blood loss from an arrow wound would not necessarily clear all enzymes that could break down tissue.

The doctor refuses to prescribe antibiotics to the patient because the illness is caused by a virus. The common cold is a viral infection of the upper respiratory tract. Antibiotics are not effective against viral infections and are only used to treat bacterial infections.

The other options are not correct because they do not accurately describe the cause of the common cold and sore throat. Fungus, protist, and bacteria are not the pathogens responsible for causing the common cold.

The triple point of a substance is the temperature and pressure at which the substance exists simultaneously in solid, liquid, and gas phases ¹. In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.

The other options are not correct because they do not accurately describe the triple point of a substance. Sol, gel, and plasma are not phases that coexist at the triple.

Urea is a waste product that is formed when proteins are broken down in the body. It is excreted by the kidneys in urine, but small amounts can also be excreted by sweat glands in sweat.

The other options are not substances that are excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia. Lysozymes are enzymes that break down bacterial cell walls, water is a component of sweat but is not specifically related to protein breakdown, and sebum is an oily substance produced by sebaceous glands to lubricate the skin.

An efferent neuron that is responsible for releasing a neurotransmitter that stimulates a muscle cell to contract is a motor neuron ². Motor neurons carry signals from the brain to the peripheral nervous system in order to initiate an action. The neurotransmitter acetylcholine (ACh) is released by motor neurons at the neuromuscular junction in skeletal muscle, causing the muscle to contract ³.

The other options are incorrect because they do not accurately describe the type of neuron responsible for releasing a neurotransmitter that stimulates a muscle cell to contract. Interneurons are found within the central nervous system and facilitate communication between sensory and motor neurons. Sensory neurons carry information from sensory receptors to the central nervous system. Neuroglia are support cells for neurons and do not transmit nerve impulses.

Both digestion and absorption happen in the small intestine ¹. Digestion is the process by which food is broken down into small molecules that the body can absorb and use for energy, growth, and repair ¹. The final products of digestion are absorbed from the digestive tract, primarily in the small intestine ¹.

The other options are not correct because they do not accurately describe where both digestion and absorption happen in the digestive system. The gallbladder stores bile produced by the liver, but does not play a direct role in digestion or absorption. The esophagus transports food from the mouth to the stomach, but does not play a direct role in digestion or absorption. The stomach plays a role in digestion by churning food and mixing it with gastric juices, but most absorption occurs in the small intestine.

The correct answer is c. Fibrinogen. Fibrinogen is a protein present in blood plasma that plays a key role in blood clotting. When an injury occurs and bleeding begins, fibrinogen is converted into fibrin, which forms a mesh-like structure that helps to trap blood cells and form a clot.

A. Monocytes are a type of white blood cell, not a protein present in blood plasma.

B. Platelets are cell fragments that play a role in blood clotting, but they are not a protein present in blood plasma.

D. Lymphocytes are a type of white blood cell, not a protein present in blood plasma.

The myelin sheath is a protective membrane that wraps around parts of certain nerve cells.

Its fatty-protein coating provides protective insulation for your nerve cell like the plastic insulation covering that encases the wires of an electrical cord ².

This allows the electrical impulses to travel quickly and efficiently between one nerve cell and the next. The other options are incorrect because they do not describe the functions of the myelin sheath.

Regeneration, sensory perception, and nutrition are not functions performed by the myelin sheath for a nerve cell.

The layer of skin that lacks blood vessels is the epidermis. The epidermis is the thin outer layer of the skin and does not have any blood vessels within it. It is composed of keratinized, stratified squamous epithelium and is made of four or five layers of epithelial cells, depending on its location in the body.

The other options are not correct because they do contain blood vessels. The papillary layer is part of the dermis, which contains blood vessels. The reticular layer is also part of the dermis and contains blood vessels . The hypodermis is a layer below the dermis and also contains blood vessels.