Answer the following question given this paragraph: Enzymes are involved in most of the chemical reactions that take place in organisms. About 4,000 such reactions are known to be catalyzed by enzymes, but the number may be even higher. In animals, an important function of enzymes is to help digest food. Digestive enzymes speed up reactions that break down large molecules of carbohydrates, proteins, and fats into smaller molecules the body can use. Without digestive enzymes, animals would not be able to break down food molecules quickly enough to provide the energy and nutrients they need to survive. Q: What substances are involved in most of the chemical reactions that take place in organisms, including digestion? Choices: - proteins - hormones - vitamins - enzymes A:
enzymes
(Question)
Answer the following question given this paragraph: Some animals communicate with scent. They release chemicals that other animals of their species can smell or detect in some other way. Ants release many different chemicals. Other ants detect the chemicals with their antennae. This explains how ants are able to work together. The different chemicals that ants produce have different meanings. Some of the chemicals signal to all of the ants in a group to come together. Other chemicals warn of danger. Still other chemicals mark trails to food sources. When an ant finds food, it marks the trail back to the nest by leaving behind a chemical on the ground. Other ants follow the chemical trail to the food. Q: What part of the body do ants use to detect chemicals? Choices: - thorax - fins - eyes - antennae A:
(Answer)
antennae
Ques: Answer the following question given this paragraph: One force acting on youand all the other objects on Earthis gravity. Look at the physics book in the Figure below . Gravity pulls the book downward with a force of 20 Newtons. Why doesn't the book fall to the ground? The table pushes upward on the book with the same amount of force. The combined force, or net force , acting on the book is 0 Newtons. That's because upward and downward forces are balanced, so they cancel out. You can learn more about net force at this URL:. Q: The pull of gravity is expressed as a force of what? Choices: - joule - pascal - volt - newtons A:
Ans: newtons
(Q).
Answer the following question given this paragraph: The human nerve cell in Figure below is a good example of a specialized animal cell. Its shape suits it for its function of sending nerve signals to other cells. A nerve cell couldn't take this shape if it were surrounded by a rigid cell wall. Q: With a shape that specially suits its function of sending nerve signals to other cells, the human nerve cell is an example of what? Choices: - adaptation - maturation - evolution - specialization A:
(A).
specialization
Ques:Answer the following question given this paragraph: Role of Feedback Loops The contribution of feedback loops to homeostasis will only be briefly reviewed here. Positive feedback loops are characterized by the release of additional hormone in response to an original hormone release. The release of oxytocin during childbirth is a positive feedback loop. The initial release of oxytocin begins to signal the uterine muscles to contract, which pushes the fetus toward the cervix, causing it to stretch. This, in turn, signals the pituitary gland to release more oxytocin, causing labor contractions to intensify. The release of oxytocin decreases after the birth of the child. The more common method of hormone regulation is the negative feedback loop. Negative feedback is characterized by the inhibition of further secretion of a hormone in response to adequate levels of that hormone. This allows blood levels of the hormone to be regulated within a narrow range. An example of a negative feedback loop is the release of glucocorticoid hormones from the adrenal glands, as directed by the hypothalamus and pituitary gland. As glucocorticoid concentrations in the blood rise, the hypothalamus and pituitary gland reduce their signaling to the adrenal glands to prevent additional glucocorticoid secretion (Figure 17.6). Q: By allowing blood levels of a hormone to be regulated within a narrow range, feedback loops contribute to maintaining what state? Choices: - hypothesis - hibernation - consciousness - homeostasis A:

Ans:homeostasis
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