Answer:
a maybe correct me if im wrong
<span>Invertebrate<span>, </span>any animal that lacks a vertebral column, or backbone, in contrast to the cartilaginous or bony vertebrates. More than 90 percent of all living animal species are invertebrates. Worldwide in distribution, they include animals as diverse as sea stars, sea urchins, earthworms, sponges, jellyfish, lobsters, crabs, insects, spiders, snails, clams, and squid. Invertebrates are especially important as agricultural pests, parasites, or agents for the transmission of parasitic infections to humans and other vertebrates. Invertebrates serve as food for humans and are key elements in food chains that support birds, fish, and many other vertebrate species.Apart from the absence of a vertebral column, invertebrates have little in common. Indeed, they are distributed between more than 35 phyla. In contrast, all vertebrates are contained within a single phylum, the Chordata. (Phylum Chordata also includes the sea squirts and some other invertebrate groups.) Invertebrates are generally soft-bodied animals that lack a rigid internal skeleton for the attachment of muscles but often possess a hard outer skeleton (as in most mollusks, crustaceans, and insects) that serves, as well, for body protection.</span>
<h2>B is the correct answer!</h2><h3 /><h3>Common sense, really. You wouldn't find fossils in the air.</h3>
Answer:
a. PK2 activates PK1
b. no response would be produced
Explanation:
Kinases are enzymes known to phosphorylate different substrates, thereby activating/inactivating them. In this case, a mutation that produces a constitutively (permanently) active PK1 kinase is itself able to continue the signaling pathway, independently of whether or not PK2 is present. This constitutive mutation shows that PK1 is recruited to continue signaling events within the cell and, therefore, PK1 activation is downstream in the signaling pathway. Conversely, cells containing active PK2 and inactive PK1 would be unable to continue the signaling pathway since PK2 activation is upstream of the induction of PK1, and thereby these cells cannot respond to the signal (PK2 activation).