Answer the following question given this paragraph: Scientists think that protists are the oldest eukaryotes. If so, they must have evolved from prokaryotic cells. How did this happen? The endosymbiotic theory provides the most widely-accepted explanation. That's because it is well supported by evidence. Q: What do many scientists think are the oldest eukaryotes? Choices: - prokaryotes - plants - arthropods - protists A:
protists
(Question)
Answer the following question given this paragraph: A unique feature of echinoderms is their water vascular system . This is a network of canals that extend along each body part. In most echinoderms, the canals have external projections called tube feet (see Figure below ). The feet have suckers on the ends. Muscle contractions force water into the feet, causing them to extend outward. As the feet extend, they attach their suckers to new locations, farther away from their previous points of attachment. This results in a slow but powerful form of movement. The suckers are very strong. They can even be used to pry open the shells of prey. Q: What makes echinoderms force water into the feet and move forward? Choices: - spring contractions - vacuum contractions - field contractions - muscle contractions A:
(Answer)
muscle contractions
Ques: Answer the following question given this paragraph: Basic Principles of Gas Exchange Gas exchange during respiration occurs primarily through diffusion. Diffusion is a process in which transport is driven by a concentration gradient. Gas molecules move from a region of high concentration to a region of low concentration. Blood that is low in oxygen concentration and high in carbon dioxide concentration undergoes gas exchange with air in the lungs. The air in the lungs has a higher concentration of oxygen than that of oxygen-depleted blood and a lower concentration of carbon dioxide. This concentration gradient allows for gas exchange during respiration. Partial pressure is a measure of the concentration of the individual components in a mixture of gases. The total pressure exerted by the mixture is the sum of the partial pressures of the components in the mixture. The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture. This concept is discussed further in detail below. Q: Gas exchange during respiration occurs primarily through what? Choices: - vaporization - secretion - activation - diffusion A:
Ans: diffusion
(Q).
Answer the following question given this paragraph: Q: A diploid zygote is formed when one sperm does what? Choices: - cracks the egg - repels the egg - incapacitates the egg - fertilizes the egg A:
(A).
fertilizes the egg
Ques:Answer the following question given this paragraph: Q: Much of what type of radiation that strikes the planet is reflected back into space? Choices: - magentic radiation - gamma rays - microwaves - solar radiation A:

Ans:solar radiation
Question: Answer the following question given this paragraph: Along with the skin, the integumentary system includes the nails and hair. Both the nails and hair contain the tough protein, keratin. The keratin forms fibers, which makes your nails and hair tough and strong. Keratin is similar in toughness to chitin, the carbohydrate found in the exoskeleton of arthropods. Q: What is the name of the protein that is found in hairs and nails? Choices: - cellulose - chromatin - Skin - keratin A:
Answer:
keratin