To prevent blood flowing back after each heartbeat. They ensure that the blood flows only in one direction (back to the heart).
Answer:Polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds.
Explanation:
Answer:
Which statement explains what happens to older crust during seafloor spreading?
Explanation:
D. It moves away from a mid-ocean ridge.
Give brainiest?
1) Chordata=A chordate is an animal of the phylum Chordata. All chordates possess 5 synapomorphies, or primary characteristics, at some point during their larval or adulthood stages that distinguish them from all other taxa
2) Vertebrates=vertebrate, also called Craniata, any animal of the subphylum Vertebrata, the predominant subphylum of the phylum Chordata. The vertebrates are also characterized by a muscular system consisting primarily of bilaterally paired masses and a central nervous system partly enclosed within the backbone.
3)Invertebrates=Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the chordate subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks, annelid, and cnidarians.
4) Poikilothermic animals=A poikilotherm is an animal whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress.
5) Homeothermic animals=The term homeothermic refers to the warm-blooded animals which have constant and relatively higher temperature. They are animals which can maintain their internal body temperature. Complete answer: Homeothermic animals are warm-blooded and maintain a constant body temperature, for example birds and mammals.
6) Oviparous= producing young by means of eggs which are hatched after they have been laid by the parent, as in birds.
7)Vivaparous=bringing forth live young which have developed inside the body of the parent
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