Answer:
Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same.
These preparations are called Vaccines. A vaccine is a biological preparation that provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing micro-organism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins.
Answer:
Pine trees produce seeds in cones
Explanation:
What are the options? you can use DNA technology to fix specific proteins for different people
Crossing over and individual chromosone assortment
