Answer: The question is not complete, here is the completed part gotten from other website.
Mammals and turtles are more closely related than are lungfishes and sharks. Hagfishes, lungfishes, and frogs have lobed fins.
Lancelets and coelacanths are more closely related than are chimaeras and coelacanths.
Organism (a) is a common ancestor of all chordates.
Descendants of organism (d) have limbs with digits. birds and ray-finned fishes have a notochord and jaws.
rays and frogs have vertebrae. organism (c) is a common ancestor of lampreys and lungfishes?
The correct options are;
Mammals and turtles are more closely related than are lungfishes and sharks.
Descendants of organism (d) have legs.
Rays and frogs have a vertebral column.
-Birds and ray-finned fishes have a notochord and jaws
Explanation:
This is because phylogenetic tree is a branching diagram that entails different evolutionary relationships that occur between organisms or biological species having common decent or ancestors and showing similar and differences in their genetic characteristics or traits. It shows how species evolved from their ancestors.
The nociceptor does not relay any information to the brain about stimuli below the threshold. This is because stimuli below the threshold do not generate an action potential and thus the neuron is not actively signalling.
Answer:
In the ocean
Explanation:
Ecological divergence leads to selection of essential traits against migrants and hybrid species. The full body plate type traits requires attention for occurrence in an environment which is free from issues such as resource limitation or predator attacks. In vast ocean spaces , resources are not a limiting factor in ocean and also there is no risk of predators as there is huge chunk of space, thus, full body plate type will occur in higher number in the ocean.
hope it helps you..
Answer: it is positive
Explanation:
Lac operon is a cluster of 3 structural gene protein involves in lactose metabolism.
Inducible operons have proteins that can bind to either activate or repress transcription depending on the local environment and the needs of the cell. The lac operon is a typical inducible operon which operates both systems, the Lac is a repressor that turns off transcription of the operon which negatively controls it by binding to the operator.
Normally, the operons are turned off, they only take charge when glucose levels are low or in the presence of lactose for digestion. To do so, the cAMP–CAP protein complex serves as a positive regulator to induce transcription. One such sugar source is lactose. The lac operon encodes the genes necessary to acquire and process the lactose from the local environment, which includes the structural genes lacZ, lacY, and lacA. lacZ encodes β-galactosidase (LacZ), an intracellular enzyme that cleaves the disaccharide lactose into glucose and galactose. lacY encodes β-galactoside permease (LacY), a membrane-bound transport protein that pumps lactose into the cell. lacA encodes β-galactoside transacetylase (LacA), an enzyme that transfers an acetyl group from acetyl-CoA to β-galactosides. Only lacZ and lacY appear to be necessary for lactose catabolism.
CAP (catabolite activation protein) binds to the operator sequence upstream of the promoter that initiates transcription of the lac operon. The lac operon uses a two-part control mechanism to ensure that the cell expends energy producing β-galactosidase, β-galactoside permease, and thiogalactoside transacetylase (also known as galactoside O-acetyltransferase) only when necessary. However, for the lac operon to be activated, two conditions must be met as stated above. First, the level of glucose must be very low. Second, lactose must be present. If glucose is absent, then CAP can bind to the operator sequence to activate transcription. If lactose is absent, then the repressor binds to the operator to prevent transcription. If either of these requirements is met, then transcription remains off. The cell can use lactose as an energy source by producing the enzyme b-galactosidase to digest that lactose into glucose and galactose. Only when both conditions are satisfied is the lac operon transcribed.
