Answer the following question given this paragraph: The theory of evolution by natural selection explains how populations of organisms can change over time. As environments change, so must the traits of organisms if they are to survive in the new conditions. Evolution by natural selection explains how this happens. It also explains why there are so many different species of organisms on Earth today. You can see examples of the incredible diversity of living animals in Figure below . You can read more about the theory of evolution in the chapter Evolution. Q: Which theory explains how populations of organisms can change over time? Choices: - free by natural selection - changes by natural selection - intelligent selection - evolution by natural selection A:
evolution by natural selection
(Question)
Answer the following question given this paragraph: Erosion moves sediments after they have formed. The sediments are transported away from the place where they form. There are several agents of erosion. Flowing water moves and deposits sediments. Water erodes far more material than any other erosional agent. Wind is important as an agent of erosion. This is especially true in arid climates. Ice, in glaciers, can erode enormous quantities of sediments. Gravity as a force of erosion pulls material downhill. Q: What moves sediments after they have formed? Choices: - photosynthesis - migration - perspiration - erosion A:
(Answer)
erosion
Ques: Answer the following question given this paragraph: Frogs and toads are adapted for jumping. Salamanders and newts may walk or swim. Caecilians live in the water or soil and are the only amphibians without legs. Q: What is the only amphibian without legs? Choices: - alligators - frogs - newts - caecilians A:
Ans: caecilians
(Q).
Answer the following question given this paragraph: It is believed that large mutations form new genes. Mutations that duplicate large sections of DNA are a major source of genetic material for new genes. It is thought that tens to hundreds of genes are duplicated in animal genomes every million years. Most genes belong to larger families of genes of shared ancestry. These gene families have domains within the protein with a particular and independent function. These domains have corresponding conserved regions within their genes. It is through duplication mutations that such gene families formed. Genetic recombination after duplication of different domains forms new combinations of domains with new functions. For example, the human eye uses four genes to make structures that sense light: three for color vision and one for night vision; all four arose from a single ancestral gene. Q: What is essential for forming new genes? Choices: - enough mutations - enough chromosomes - chromosome deversity - large mutations A:
(A).
large mutations
Ques:Answer the following question given this paragraph: Hydrogen Bonds Ionic and covalent bonds are strong bonds that require considerable energy to break. However, not all bonds between elements are ionic or covalent bonds. Weaker bonds can also form. These are attractions that occur between positive and negative charges that do not require much energy to break. Two weak bonds that occur frequently are hydrogen bonds and van der Waals interactions. These bonds give rise to the unique properties of water and the unique structures of DNA and proteins. When polar covalent bonds containing a hydrogen atom form, the hydrogen atom in that bond has a slightly positive charge. This is because the shared electron is pulled more strongly toward the other element and away from the hydrogen nucleus. Because the hydrogen atom is slightly positive (+), it will be attracted to neighboring negative partial charges (). When this happens, a weak interaction occurs between the + charge of the hydrogen atom of one molecule and the charge of the other molecule. This interaction is called a hydrogen bond. This type of bond is common; for example, the liquid nature of water is caused by the hydrogen bonds between water molecules (Figure 2.7). Hydrogen bonds give water the unique properties that sustain life. If it were not for hydrogen bonding, water would be a gas rather than a liquid at room temperature. Q: Breaking of weak bonds, which tend to form between positive and negative charges, does not require much what? Choices: - catalyzation - heat - time - energy A:

Ans:energy
Ques: Answer the following question given this paragraph: During sexual reproduction, two parents are involved. Most animals are dioecious , meaning there is a separate male and female sex, with the male producing sperm and the female producing eggs. When a sperm and egg meet during fertilization , a zygote , the first cell of a new organism, is formed ( Figure below ). This process combines the genetic material from both parents. The resulting organism will be genetically unique. The zygote will divide by mitosis and grow into the embryo. Q: In dioecious animals, females generally produce what contribution to reproduction? Choices: - milk - warmth - intelligence - eggs A:
Ans:
eggs