B. sexual selection, which alters allele frequencies in the gene pool.
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The breathing process occurs as follows: Inhalation increases the volume of the lungs, which reduces internal pressure and causes air to enter. Then the exhalation makes the opposite process. Gaseous exchanges occur in the lung alveoli and are responsible for eliminating the gases we do not need and preparing the oxygen to be spread throughout the body.
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Answer:
1. Muscle Fibers
2. Bones
3. Joints
Explanation:
Muscle tissue is made of muscle fibers. The plasma membrane of a muscle fiber is called sarcolemma while its cytoplasm is known as sarcoplasm. Muscle cells are characterized by the presence of specialized endoplasmic reticulum which is called sarcoplasmic reticulum.
Muscle cells exhibit contractility and extensibility. The ability of muscle cells to shorten their length forcibly in response to a stimulus is their contractility. Muscle fibers have the ability to extend and shorten themselves.
Extension and contraction of muscle fibers are responsible for the movement of the human body and its parts.
Muscles are attached to bones via tendons which in turn are the fibrous connective tissues. Muscles are also part of our joints where they assist in the movement by pulling the bones as well as stabilize and strengthen the joints.
The<u> repressor </u>is a type of regulator protein that binds to a region of DNA in the promoter of a gene called the operator and prevents transcription from taking place.
In the field of science, a regulator protein can be described as a kind of protein that affects the transcription of a gene by having an influence on particular DNA sites. The rate of synthesis of various proteins is controlled by the regulator proteins.
A repressor is a kind of regulator protein that prevents the transcription of a particular gene. When the rate of a protein in the body has reached normal, the transcription of the protein needs to be stopped in order for more protein of that kind to be formed. The repressor binds itself to the operator region for the gene, hence stopping the transcription process until the protein is required again.
To learn more about repressor, click here:
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The small intestine has cilia to absorb nutrients and reabsorb water
