Answer: "Decreasing the salt concentration of the solution lowers DNA's melting point (Tm)" is not a true statement
Explanation:
Increasing salt concentration would lower the DNA's melting point (Tm), not otherwise.
For instance:
- In 8M urea (8M means 8 Moles per dm3), Tm is decreased by nearly 20°C.
- 95% formamide at room temperature would completely denature the double stranded DNA.
Thus, higher concentration of salts like urea or formamide lowers Tm, not otherwise
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Answer:
The cell membrane is semipermeable because allows only certain molecules to pass through.
Explanation:
Semipermeability is a common property of cell membranes, due to their predominantly lipid composition, which gives them a hydrophobic character.
The cytoplasmic membrane is constituted by a double layer of lipids, in addition to structural proteins and glucides, which prevent the entry of polar or charged molecules. This characteristic allows lipids and small molecules without charge to pass freely through it.
Regarding the other options:
<em> A. Cell membranes are associated with lysosomes, structures that contain enzymes. However, this characteristic is not related to semipermeability.</em>
<em> C. They allow the passage of small molecules - devoid of charge - through them.</em>
<em> D. Not all non-polar molecules pass through, as some need a transporter.</em>
Answer: the beaks of the finches are adapted to the way the bird usually gets food. :) good luck!
Take for example - you touching something sharp and instantly moving your hand away.
Sensory neurons in your fingers detect the external stimuli of the sharp object and send a nerve impulse to the spinal cord (does not reach brain) and is sent back to a motor neurone - attached to an effector that moves the muscle and moves the hand away. This is a rapid reflex action and involuntary.
