Calcium has an atomic number of 20; therefore, calcium has 20

protons

protons plus neutrons

shells

Where is the magnet that causes Earth's magnetic field located? What is this magnet made of?

List two natural disturbances and two human-made disturbances that can lead to succession

Which type of scientific statement is defined as the statement of fact that is generally excepted into be true in universal because it has always been observed to be true? Theory, probability, law, hypothesis

What is the highest level of protein structure in each of the protein examples below?

Which of the following events occurs during Meiosis I? The number of chromosomes increases from the haploid number to the diploid number. Non-sister chromatids are separated from each other. Sister chromatids are separated from each other.

Dna stands for what in biology

Coal is used to produce energy. The harmful gases produced by coal are cleaned up by a method which needs a large amount of limestone. Predict and explain the long term effect on the environment of obtaining and using limestone.

True or false two genes may not segregate independently if they are on the same chromosmoe

Blood pressure rises and falls in a pattern corresponding to the phases of the

Immune system cells enter a resting phase after undergoing mitosis. when activated-for example, by an infection-they can reenter the sequence of events in the cell cycle that leads to cell division.