The skin acts as a physical barrier and prevents foreign substances entering the body. In which system is the skin playing a role by performing this function?

What is the result of mitosis? A. one sperm and one egg B. two genetically identical nuclei C. four genetically identical nuclei D. two sperm cells and two eggs

Name three different allotropes of carbon and describe their physical properties

Which human activity negatively affects the stability of the environment

Arctic ice retreat is threatening many species in this ecosystem. Their resources are being cut and they are needing to find new ways to survive.

Mitochondria and chloroplasts are thought to have evolved from free-living aerobic bacteria that were engulfed by an ancestral anaerobic cell and established a mutually beneficial (symbiotic) relationship with it.

Why do rocks vary in color?

In which horizon of a soil profile is the parent material usually found?

Match these items. 1. new varieties of roses animal husbandry 2. new varieties of chickens archaeology 3. beginnings philosophy 4. a body of personal ideas and opinions plant breeding 5. ancient history, cultures origin

Read the passage below. It summarizes survey information. The Global Youth Tobacco Survey asks youth to fill in the answers to several questions about their tobacco use.

Dysfunctional breathing results in an increase in the activity level of which of the following secondary respiratory muscles a. Scalenes b. Rectus abdominis c. Internal oblique d. Diaphragm