Solved by verified expert:Paraphrase answers that correspond to their questions The word Doc is attached below It is on Excretory System and Digestive System
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1. Compare the digestive tract of a planarian with that of an earthworm.
a. Planarians have a gastrovascular cavity with only one opening that is the entrance
and exit. An earthworm, on the other hand, has a complete digestive tract
including a mouth and anus. Also the absorptive surface of the intestines is
increased by the internal folds (typhlosole).
2. Describe some of the limitations of an incomplete digestive tract.
The limitations include being limited to the type of food that it can feed on, no cell can be
very far from the digestive tract, and it does not have specialized parts. The fact that the digestive
tract is incomplete limits the evolution of more specialized parts.
3. Compare the teeth of carnivores to those of herbivores.
Herbivores often have sharp, even incisors to help clip off vegetation, and large, flat
premolars and molars that are adapted for extensive grinding and crushing of plant cell walls.
Carnivores have canine teeth for killing, short incisors for scraping bones, and pointed molars for
4. Describe the likely selective pressures that resulted in the evolution of taste buds.
Because they are chemically stimulated by the chemical composition of food, the
selective factors for taste bud evolution probably depended largely on the available diet. This
would allow for animals to taste which foods may have been more desirable or nutritious,
enabling ancestor survival. Furthermore, they are dependent on the selective pressures that
resulted in the evolution of the tongue and surface of the mouth.
5. Explain how the stomach, small intestine, and large intestine are each adapted to
perform their particular functions.
Stomach: Because the wall has deep folds, it is able to fill to its accommodate its capacity
for food. This allows for animals to eat periodically and large meals so they spend the remainder
of their time investing in other metabolic activities. In addition to being a food storage, the
muscular walls contract and mix food with juices (very acidic and contains pepsin) to allow for
the facilitation of digestion. The epithelial lining has gastric pits to produce gastric juice, and a
thick layer of mucus protects the stomach wall from enzymatic action.
Small Intestine: It has a small diameter but long length, containing the duodenum that
brings bile from the liver and gallbladder, as well as pancreatic juice. The large surface area is
highly responsible for its function, including absorbing nutrients into the villus.
Large Intestine: The cecum, colon, rectum, and anus allow it to absorb water, salts, and
vitamins. These structures also allow the large intestine to store any material that is not
digestible, which is then eliminated as feces.
6. Explain what final molecule (monomer) results from the digestion of carbohydrates,
proteins, and fats.
Carbohydrates are broken down into sugars, proteins are broken down into amino acids,
and fats are broken down into lipids.
7. Review several reasons why a diet that includes plenty of vegetables is generally
better for you than a diet that includes excess protein.
More water consumption is needed to digest excess protein, leading to dehydration.
Furthermore, high protein diets can cause calcium loss and create kidney stones, and they can
contain a large amount of fat to be stored in the body since it can not process the excessive
amount of protein.
8. Discuss the relationship between blood cholesterol, saturated fat intake, and
Diets that are high in saturated fats, trans fats, and cholesterol raise LDL levels. This
contributes to the likelihood of developing cardiovascular disease, and if a person’s cholesterol
and triglyceride levels are elevated, the fat content of the diet and exercise are imperative to
reduce the risk of cardiovascular disease.
9. Define vitamin.
Vitamins are organic compounds (non carbohydrate, fat, or proteins) that regular
metabolic activities and are present in the diet.
1. Distinguish between osmoregulation and excretion.
Osmoregulation is balancing levels of water and salts in the body, while excretion is the
removal of metabolic wastes from the body (which often uses the osmoregulatory system).
2. Describe two advantages of excreting urea instead of ammonia or uric acid.
It is much less toxic and can be excreted in a more concentrated way, conserving the
water in the body to help animals that have limited access to water.
3. Summarize the strategies used by kangaroo rats to conserve water.
It remains in a cool burrow during the day, has convoluted mucous membrane surfaces in
the nasal passage that captures the water from the exhaled air. It also has hypertonic urine, with
drinks very little water, and produces very dry fecal material.
4. Describe which of the four major functions of the human urinary system are
accomplished solely by the kidneys, and which are shared with other body systems.
They excrete metabolic waste, maintain the water salt balance, maintain the acid base
balance (pH, reliant on respiratory system), and secrete hormones (also relies on cardiovascular
system to send out hormones).
5. Explain the effect of the renin-angiotensin-aldosterone system on water-salt balance.
Renin is an enzyme that transforms angiotensin I to angiotensin II, which is a
vasoconstrictor that stimulates the adrenal glands on top of the kidneys. This releases
aldosterone, a hormone promoting the excretion of potassium ions and absorbing sodium ions.
This allows for water to be reabsorbed and increases the blood volume and blood pressure.
6. Describe how the kidneys contribute to the maintenance of normal blood pH.
The bicarbonate buffer system and breathing work together, and as carbon dioxide is
excreted by the lungs, the blood pH will begin to rise, depressing the respiratory center and the
bicarbonate ion concentration increases. The kidneys help rid the body of a wide range of acid
and basic substances.
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