What are two ways that the size of a population can increase ? what are two ways that the size of a population can decrease

For population increase two factors or ways are described which are birth or death, immigration and emigration.

The two ways a population can decrease is through mortality and emigration.

Explanation:

A population's increase is resolved  by  death, birth, immigration, and emigration. When a population's birthrate is higher than its death rate the population size, The population size is rises.

Also,The two factors responsible for the decrease in size of a population are emigration, which is the migration of an individual from a place. and mortality, which is the number of individual deaths in a population over a period of time.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.