Answer:the possession of feathers
Explanation:birds are warm blooded animals , that possess feathers.these feathers cover their bodies and used for flight and warmth.their forelimbs are modified into wings,which fold into a Z shape at rest.feathers grow from the skin follicles and are replaced by scales on their legs.they possess oil gland to dress the feathers.
Other features of birds include
1) beaks with no teeth
2) fully ossified bones with air cavities
3)females with left ovary and oviducts only
Answer:
Constitutive activation is the alteration of a protein or signaling pathway such that it is functional or engaged even in the absence of an upstream activating event. For example, RasD is constitutively active because it cannot bind GAP and therefore remains in the GTP-bound, active state even when cells are not stimulated by growth factor to activate a receptor tyrosine kinase.
Constitutively active Ras is cancer promoting because cells will proliferate in the absence of growth factors, and thus normal regulatory mechanisms for cell proliferation are bypassed.
(a) A mutation that resulted in Smad3 binding Smad4, entering the nucleus, and activating transcription independent of phosphorylation by the TGFβ receptor would render Smad3 constitutively active.
(b) A mutation that made MAPK active as a kinase and able to enter the nucleus without being phosphorylated by MEK would render MAPK constitutively active.
(c) A mutation that prevented NF-KB from binding to IK-B or that allowed NF-KB to enter the nucleus and regulate transcription even when bound to IK-B would render NF-KB constitutively active.
Answer:
A longshore current is when the wave reaches the coastline and release bursts of energy.An which it can run parallel to the shoreline.
Explanation:
I cannot found the images of the microscopy anywhere. But I can explain how you can differentiate a procaryote from a eucaryote under a microscope.
The first difference between them is the size of the cell. eucaryotes are generally much bigger than procaryotes. Procaryotes are visible only at x100 objective, but eucaryotes are visible starting from the x10 zoom.
The second difference is the presence of a nucleus in eukaryotes and the absence of it in procaryotes.
The third difference is the presence of organelles in eukaryotes and the presence of a cell wall in procaryotes (only visible at electronic microscopy).
