What does this symbol mean, and which safety precaution must be taken when it is present?

Which best explains how a heat pump can heat a room? cold air from the house is moved through pipes, where it absorbs thermal energy. warm air from outside is pushed into the house to replace the cold air. combustion warms the air when chemical energy is transferred to thermal energy. fuel is used to move a piston, which pushes warm air into the house.

In a population that is in hardy-weinberg equilibrium, there are two possible alleles for a certain gene, a and a. if the frequency of allele a is 0.4, what fraction of the population is heterozygous? a. 0.40 b. 0.60 c. 0.16 d. 0.48

What is the function of the root cap? a. extra-absorbent cells in the root cap absorb more water and nutrients b. protect the meristematic area of the stem c. contains sensors for sunlight d. increases surface area of the root