Active transport uses energy passive transport does not..... active transport moves from lower to higher concentration and vice versa in passive transport.... both use carrier proteins....
I believe the answer is 1/2
Scientists change scientific theories when new evidence conflicts with old ideas; option D
<h3>What are scientific theories?</h3>
Scientific theories are explanations put forward by scientists to explain a given observation based on current research.
Scientific theories can be modified based on changing evidence due to further research.
Therefore, it can be concluded that when new evidence disproves old ideas, scientists modify and adjust scientific theories to harmonize with new evidence.
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Veins being squeezed between contracting muscles to help pump blood toward the heart is known as the Skeletal muscle pump.
The Skeletal muscle pump is a group of skeletal muscles which assists the heart in the blood circulation. It is specifically significant in increasing venous return to the heart, however it may also perform a part in arterial blood flow.
Skeletal muscles aid in bringing venous blood back to the heart, particularly in the lower limbs.
Veins inside the muscle are squeezed in response to the muscle contraction and this functionally serves as a secondary pump. This process pushes the blood, which would else be stockpiled in the lower limbs, back to the heart.
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There are three types of variation mutation, recombination and immigration so your answer is mutation
