Ques:Q: What do corals secrete that builds up to become a coral reef? Read this paragraph and choose the correct option from the provided answers: Cnidarians include jellyfish and corals. They are aquatic invertebrates. They have tissues and radial symmetry. They also have tentacles with stingers. There are two cnidarian body plans: the polyp and the medusa. They differ in several ways. Many corals secrete an exoskeleton that builds up to become a coral reef. Choices: - membrane - mucous - scales - exoskeleton A:

Ans:exoskeleton
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Ques:Q: What makes echinoderms force water into the feet and move forward? Read this paragraph and choose the correct option from the provided answers: 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. Choices: - spring contractions - vacuum contractions - field contractions - muscle contractions A:

Ans:muscle contractions
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Ques:Q: What is the term for a galaxy that is a rotating disk of stars and dust? Read this paragraph and choose the correct option from the provided answers: A spiral galaxy is a rotating disk of stars and dust. In the center is a dense bulge of material. Several spiral arms come out from the center. Spiral galaxies have lots of gas and dust and many young stars. The image below ( Figure below ) shows a spiral galaxy from the side. You can see the disk and central bulge. Choices: - cosmic galaxy - nebula - Milky Way - spiral galaxy A:

Ans:spiral galaxy
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Ques:Q: What happens to the recessive traits in the offspring of a hybridization? Read this paragraph and choose the correct option from the provided answers: Upon compiling his results for many thousands of plants, Mendel concluded that the characteristics could be divided into expressed and latent traits. He called these, respectively, dominant and recessive traits. Dominant traits are those that are inherited unchanged in a hybridization. Recessive traits become latent, or disappear, in the offspring of a hybridization. The recessive trait does, however, reappear in the progeny of the hybrid offspring. An example of a dominant trait is the violet-flower trait. For this same characteristic (flower color), white-colored flowers are a recessive trait. The fact that the recessive trait reappeared in the F2 generation meant that the traits remained separate (not blended) in the plants of the F1 generation. Mendel also proposed that plants possessed two copies of the trait for the flower-color characteristic, and that each parent transmitted one of its two copies to its offspring, where they came together. Moreover, the physical observation of a dominant trait could mean that the genetic composition of the organism included two dominant versions of the characteristic or that it included one dominant and one recessive version. Conversely, the observation of a recessive trait meant that the organism lacked any dominant versions of this characteristic. Choices: - they dominate - remain recessive - they replicate - they disappear A:

Ans:
they disappear
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