Answer:
To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the right concentrations of ions and molecules in living cells.
Explanation:
Answer: pressure changes
Valves of the heart open and close due to pressure changes
Explanation:
The veins are the blood vessels possessing valves. And because they carry blood away from the heart, the valves helps to prevent back flow of blood due to the low pressure of blood found in the veins.
Thus, Valves of the heart open and close due to pressure changes
The answer is graduated cylinder.
Dani requires a graduated cylinder to measure
the volume of the pebbles. A graduated cylinder is actually laboratory
equipment to measure the volume of a liquid. Dani must place a specific amount
of liquid in the cylinder and record the amount. Dani will then put the pebbles
inside the cylinder and subtract the amount of liquid previously recorded to
the current amount to get the volume of the pebbles.
I believe the answer is a and d and b not 100% sure
Copying of information in DNA is also known as DNA replication.
Not sure if that's what you're looking for so lmk.
