How did oxygen first enter Earth's atmosphere

What are the two types of global food webs and how they are connected?

Which of the following conditions leads to germination of a spore into a vegetative cell? a. a nutrient rich environment b. water c. high temperatures d. all of the above leads to germination of a spore

Why does sexual reproduction result in more genetic diversity than asexual reproduction

If a mutation causes a permanent change in the DNA sequence, how is it that most mutations are "silent" mutations?

Omega-3 and omega-6 essential fatty acids are readily available in leafy green plants. What is one way to ensure that animals raised for commercial purposes have enough of these fatty acids in their diets such that fatty acid supplementation is not

Which statement is true for both plant and animals cells? They have centrioles and cellulose. Animal cells are generally smaller than plant cells. They have mitochondria and chloroplasts. They have cell nuclei and vacuoles.

What's one main difference between prokaryotic and eukaryotic cells

Why dose secondary succession occur faster than primary succession?

Freediving is an activity in which a person dives, sometimes to great depth, without the use of scuba gear. the diver must hold his or her breath for the duration of the dive.

Scientists have developed a synthetic substance that can ___. 1. be used to replace damaged brain tissue 2. conduct, or transmit, nerve impulses 3. replace damaged nerve tissue 4. grow artificial limbs