Answer:
A callus is a hardening of skin, keratin is the protein which is abundant in callus. Skin is a protective layer against a external environment. Outer layer of skin consist of keratin which is also found in hair. Callus is the accumulation of dead cells result due to friction and pressure exerts on the part in which they are present. The keratin component (keratinocytes) remains undifferentiated in these dead cells which causes hardening in callus.
Switch A and D, but other than that your answers are correct.
An astronomical body is an object in space.
A comet is a celestial object consisting of a nucleus of ice and a stream of gas and dust.
A moon is an astronomical body that orbits around a planet.
A galaxy is a system of start held by gravitational attraction.
Answer:
Archaebacteria have cell wall made of complex composition of peptidoglycan
Answer:
<u><em>Active Transport</em></u>
Explanation:
<u><em>active transport
</em></u>
During <u><em>active transport</em></u>, substances move against the concentration gradient, from an area of low concentration to an area of high concentration. This process is “active” because it requires the use of energy (usually in the form of ATP). It is the opposite of passive transport.
Medications can be tested on cell cultures instead of being injected into patients unnecessarily.
Cancer cells continue to grow in the cultures uncontrollably allowing scientists to test multiple medications on the cancer cells.
