Answer: Cells have receptors because Receptors let the cell know when to let things in and out of the cell.
Explanation:
Cell receptors also called transmembrane receptors are proteins located on the surface of a cell (extracellularly) or inside the cell which receive signals that alters the functions of the cell. The functions of the cells which can be altered includes the alteration in gene transcription and the cell morphology.
Cell receptors are generally categorizes into the following groups:
--> Internal receptors
--> cell surface receptors
--> ion channel receptors
--> G protein coupled receptors
--> enzyme linked receptors
Interaction of cell membrane receptors with specific ligands that bonds to the receptors causes conformational changes in the receptor protein. This in turn, enzymatically activates the intracellular part of the protein or induces interactions between the receptor and the proteins in the cytoplasm that act as second messengers, thereby relaying the signal from the extracellular part of the receptor to the interior of the cell. This enables the cell to know when to let things in or out of it through the information conveyed.
Answer:
c. 981 watts
Explanation:
Given:
- horizontal speed of treadmill,
- weight carried,
- grade of the treadmill,
<u>Now the power can be given by:</u>
(where grade is the rise of the front edge per 100 m of the horizontal length)
Considering conservation of momentum;
m1v1 + m2v2 = m3v3
In which,
m1 = mass of snowball 1 = 0.4 kg
v1 = velocity of snowball 1 = 15 m/s
m2 = mass of snowball 2 = 0.6 kg
v2 = velocity of snow ball 2 = 15 m/s
m3 = combined mass = 1 kg
v3 = velocity after comination
Therefore;
0.4*15 + 0.6*15 = 1*v3
v3 = 6+9 = 15 m/s
KE = 1/2mv^2
Then,
KE1 = 1/2*0.4*15^2 = 45 J
KE2 = 1/2*0.6*15^2 = 67.5 J
KE3 = 1/2*1*15^2 = 112.5 J
Therefore, KE3 (kinetic energy after collision) = K1+K2 {kinetic energy before collision). And thus it is 100%.
No. A neutron star is the weird remains of a star that blew its outer layers off
in a nova event, and then had enough mass left so that gravity crushed its
electrons into its protons, and then what was left of it shrank down to a sphere
of unimaginably dense neutron soup. But it didn't have enough mass to go
any farther than that.
A black hole is the remains of a star that had enough mass to go even farther
than that. No force in the universe was able to stop it from contracting, so it
kept contracting until its mass occupied no volume ... zero. It became even
more weird, and is composed of a substance that we don't know anything about
and can't describe, and occupies zero volume.
Contrary to popular fairy tales, a black hole doesn't reach out and "suck things in".
It's just so small (zero) that things can get very close to it. You know that gravity
gets stronger as you get closer to an object, so if the object has no size at all, you
can get really really close to it, and THAT's where the gravity gets really strong.
You may weigh, let's say, 100 pounds on the Earth. But you're like 4,000 miles
from the center of the Earth. What if all of the earth's mass was crammed into
the size of a bean. Then you could get 1 inch from it, and at that distance from
the mass of the Earth, you would weigh 25,344,000,000 pounds.
But Earth's mass is not enough to make a black hole. That takes a minimum
of about 3 times the mass of the sun, which is right about 1 million times the
Earth's mass. THEN you can get a lightweight black hole.
Do you see how it works now ?
I know. It all seems too fantastic to be true.
It sure does.
Answer:
friction reduces the efficiency of machines, thus we must reduce the friction force that is acting upon it.
