Trace fossil because a trace fossil is a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
Answer:
please mark as brainliest answer as it will also give you 3 points
Explanation:
Cyclin-dependent kinases (CDKs) are the families of protein kinases first discovered for their role in regulating the cell cycle. They are also involved in regulating transcription, mRNA processing, and the differentiation of nerve cells.[1] They are present in all known eukaryotes, and their regulatory function in the cell cycle has been evolutionarily conserved. In fact, yeast cells can proliferate normally when their CDK gene has been replaced with the homologous human gene.[1][2] CDKs are relatively small proteins, with molecular weights ranging from 34 to 40 kDa, and contain little more than the kinase domain.[1] By definition, a CDK binds a regulatory protein called a cyclin. Without cyclin, CDK has little kinase activity; only the cyclin-CDK complex is an active kinase but its activity can be typically further modulated by phosphorylation and other binding proteins, like p27. CDKs phosphorylate their substrates on serines and threonines, so they are serine-threonine kinases.[1] The consensus sequence for the phosphorylation site in the amino acid sequence of a CDK substrate is [S/T*]PX[K/R], where S/T* is the phosphorylated serine or threonine, P is proline, X is any amino acid, K is lysine, and R is arginine.[1]
Protists obtain food in 3 ways. They produce their own organic molecules, ingest, and absorb. Ingestive protists ingest food, or engulf bacteria. These protists extend their cell wall and cell membrane forming a food vacuole around the food item. Inside the food vacuole, enzymes digest the food. Absorptive protists on the other hand, absorb food molecules across their cell membrane which takes place through diffusion. Absorptive protists play a key role in decomposition. They are considered as important decomposers. Major producers like photosynthetic protists use light energy to manufacture their own food.<span>
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Answer:
Nitrogen thet cannot be used by organisms. C.
Explanation:
Free nitrogen is simply molecular nitrogen (N2). Nitrogen, in its molecular form, consists of two nitrogen atoms bound together with a tripple bond. Because it is very stable, N2 is typically nonreactive, and takes a lot of energy to break them apart. Among these are the amino acids necessary for life to begin and which are the building blocks DNA is made from. Basically, any nitrogen that is in an organic compound is considered “fixed” nitrogen and N2 is considered to be “free” nitrogen
