How is biodiversity used as a measure for the health of an ecosystem?

Ialready know the answers to these questions and they are on the attachment. but i just need to know why that answer is the correct one. plz asap! this is for a report that i need to email by 10!

Match the following terms and definitions. 1. species that are adapted to live in equilibrium at carrying capacity population density 2. population growth that reaches equilibrium and carrying capacity population 3. death rate mortality 4. birth rate k-selected 5. a group of interacting individuals of the same species within the same geographic area natality 6. the number of organisms living in a particular area logistic growth

Question 17 (1 point) where does penicillin come from? a. it is a chemical that man invented b. it is a fungus c. it is a toxin made by other bacteria d. it was discovered in archaebacteria