Bio Test #2 Review

Certain nutrients are considered "essential" in the diets of certain humans because they cannot be manufactured by the organism. This means that the body is unable to produce these nutrients on its own and therefore, they must be obtained from external sources such as food. These essential nutrients play crucial roles in various bodily functions and are necessary for maintaining overall health and well-being.

Salivary amylase is an enzyme that breaks down starch into smaller sugar molecules. Therefore, the correct answer is starch, as it is the substrate on which salivary amylase acts.

Organisms in which a circulating body fluid is distinct from the fluid that directly surrounds the body's cells are likely to have a closed circulatory system. In a closed circulatory system, blood is enclosed within vessels and is pumped by a heart, allowing for more efficient transport of nutrients, gases, and waste products throughout the body. This system provides better control and regulation of blood flow and allows for a higher metabolic rate compared to organisms with an open circulatory system, where the body fluid directly bathes the cells.

Urea is produced in the liver from NH3 (ammonia) and CO2 (carbon dioxide). The liver converts ammonia, which is a waste product of protein metabolism, into urea through a series of enzymatic reactions known as the urea cycle. The urea is then transported to the kidneys where it is excreted in urine. This process helps to remove excess nitrogen from the body and maintain a proper balance of nitrogenous waste.

A four-chambered heart would allow an organism to adjust blood pressure independently in capillaries of the gas exchange surface and in the capillaries of the general body circulation. This is because a four-chambered heart has separate chambers for oxygenated and deoxygenated blood, allowing for more efficient circulation and control of blood flow to different areas of the body. This enables the organism to regulate blood pressure independently in different areas, ensuring that gas exchange in the lungs is optimized while also providing adequate blood supply to the rest of the body.

Fishes are the only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart. This is known as single circulation, where deoxygenated blood is pumped from the heart to the gills where it picks up oxygen, and then is delivered directly to the body tissues. In contrast, mammals, birds, reptiles, and amphibians have double circulation, where blood is first pumped to the lungs or respiratory organs to pick up oxygen, and then returns to the heart before being pumped to the body tissues.

The blood level of carbon dioxide is most important in controlling human respiration rate. When carbon dioxide levels in the blood increase, it triggers the brain to increase the rate and depth of breathing in order to remove the excess carbon dioxide and bring in more oxygen. Conversely, when carbon dioxide levels decrease, the brain decreases the respiration rate to conserve carbon dioxide and maintain a balance. Therefore, carbon dioxide plays a crucial role in regulating respiration in humans.

If a newborn were accidentally given a drug that destroyed the thymus, his T cells would not mature and differentiate appropriately. The thymus is responsible for the maturation and differentiation of T cells, which are a crucial component of the immune system. Without a functional thymus, the newborn's T cells would not be able to develop properly, leading to a compromised immune response. This would result in a weakened ability to fight off infections and diseases.

During inhalation, the rib muscles and diaphragm contract, which leads to an increase in the lung volume. This increase in volume creates a lower pressure inside the lungs compared to the outside environment. As a result, gas flows from a region of higher pressure (outside the lungs) to a region of lower pressure (inside the lungs), causing air to rush into the lungs.

An osmoconformer is an organism that allows its internal osmolarity (concentration of solutes) to match the osmolarity of its environment. In this case, the environment is saltwater, which is typically hyperosmotic (higher osmolarity) compared to the internal fluids of most organisms. Therefore, the body fluids of an osmoconformer would need to be isoosmotic (equal osmolarity) with the saltwater environment in order to maintain osmotic balance.

Protein in muscle cells would be used as an energy source only after the depletion of other sources because the body prefers to use carbohydrates (such as glucose in the blood and glycogen in muscle cells) and fats (in adipose tissue) as the primary sources of energy. These sources are more easily accessible and provide energy more efficiently. Only when these sources are depleted, the body would resort to breaking down proteins in muscle cells for energy. Calcium phosphate in bone is not used as an energy source.

Urea is the primary nitrogenous waste product of humans. This means that it is the main waste product that is formed in the human body as a result of protein metabolism. Urea is produced in the liver and then excreted by the kidneys through urine. It is formed from the breakdown of amino acids and is less toxic to human cells compared to ammonia. Urea is highly soluble in water, which allows for its efficient excretion by the kidneys.

The most likely explanation for the sea star's death is that it is hyperosmotic to the freshwater, meaning that the concentration of solutes in its body is higher than in the surrounding water. As a result, the sea star was unable to osmoregulate, or maintain the balance of water and solutes in its body. This imbalance likely caused physiological stress and ultimately led to the sea star's death.

Parietal cells in the stomach are responsible for producing hydrochloric acid, which is necessary for the activation of pepsinogen into pepsin, the enzyme that breaks down proteins. Without functioning parietal cells, the individual would not be able to initiate protein digestion in the stomach.

Mast cells release histamines to initiate an inflammatory response. Histamines are signaling molecules that cause blood vessels to dilate and become more permeable, allowing immune cells and fluid to enter the affected area. This increased blood flow and permeability help to remove pathogens or foreign substances and promote the healing process. Mast cells are found in tissues throughout the body, particularly in areas that are in contact with the external environment, such as the skin and mucous membranes.

Both marine and freshwater bony fish have the feature of gaining water through food. In both environments, fish need to maintain their body water balance. They obtain water from the food they consume, which helps them compensate for the water loss through their gills. This is an important osmoregulatory mechanism for fish living in both marine and freshwater habitats.

During an inflammatory response, the body's immune system activates phagocytes, which are white blood cells that engulf and destroy pathogens. This increased activity of phagocytes helps to eliminate the infectious agents and promote healing in the inflamed area. It is an essential part of the immune response to protect the body from further harm and restore normal tissue function.

TLRs recognize specific molecules that are common to certain groups of pathogens. Among the given options, double-stranded RNA is most likely to be recognized by a particular TLR that defends against some viruses. This is because double-stranded RNA is a characteristic feature of many viruses, and TLRs can detect this molecule as a sign of viral infection. The other options, such as lipopolysaccharides, phospholipids, double-stranded DNA, and glycoproteins, are not specific to viruses and are less likely to be recognized by TLRs in the context of viral defense.