Answer:
B. The membrane lets certain substances move across it freely, while others must move through a “gate”.
Explanation:
Selective permeability is a property of cellular membranes that only allows certain molecules to enter or exit the cell. This is important for the cell to maintain its internal order irrespective of the changes to the environment. For example, water, ions, glucose and carbon dioxide may need to be imported or exported from the cell depending on its metabolic activity. Similarly, signaling molecules may need to enter the cell and proteins may need to be released into the extracellular matrix. The presence of a selectively permeable membrane allows the cell to exercise control over the quantum, timing and rate of movement of these molecules.
The three liquids will form three layers, the bottom layer is more dense and the top layer is less dense
The right answer is D (less responsive to antigens)
It is proven that, after puberty, thymus activity (an organ that is included in the lymphatic system, producing T cells that pick up antigens) decreases and that in adult and aged people the thymus has no role. Work done in humans indicate that in fact the cellularity begins to decline from birth in favor of lymphocyte perivascular spaces and connective and adipose tissue, which leads to a decrease in the capture of antigens.
Question: Which pituitary hormone causes liver cells to release somatomedins that increase the rate of uptake of amino acids by cells such as skeletal muscle fibers?
follicle-stimulating hormone
prolactin
thyroid-stimulating hormone
growth hormone
Answer:
growth hormone
Explanation:
Somatomedins are growth factors. The growth hormone makes the cells such as liver cells, skeletal muscles, bones, etc. to secrete the somatomedins. The somatomedins from the liver enter the bloodstream to reach the target cells. The somatomedins make the skeletal muscles, bones, etc. to absorb amino acids into the cells so as to facilitate protein synthesis. This growth factor also downregulates the breakdown of proteins. This is how growth hormone triggers the growth of muscles and soft tissues.
Answer:
Both options are valid, since in the hypothesis of the savanna it was argued that humans acquired bipedalism to be able to self-supply their food more effectively, and to have less body surface area exposed to the sun.
Explanation:
The saban hypothesis is believed to have originated in the saban, with the Austrolopitecus africanus being forced to affect this domain, which is why it acquired this adaptation mechanism.
The savanna had high grasslands, which also led to collaboration in this regard since they could be better camouflaged.
In addition, the human began to defend with the limbs of the upper limb, triggering the canines to decrease in size since it is not used as a defense mechanism.
The canine is a tooth that helps to tear carnivorous food, that is why the human also begins to have a more varied diet of fruits and seeds and that it can reach and take the bones of the tree to increase its height due to bipedalism.
