Why are theories modified but only rarely?

Explain why a circulatory system is important in meet the needs of all cells throughout an animal's body.

Describe what would happen to people who lost their mitochondria and explain why it would happen. Are there any "backup systems" available in this case; and would it be enough to sustain the organism?

Why does using zebrafish as a model organism for genetic testing bring up ethical concerns? As invertebrates, they have more genes than other animals. As vertebrates, they are similar to humans. As an endangered species, they need to be protected.

In the new 6-kingdom system of classification, like the old 5-kingdom system, organisms are basically grouped by what is called

Why did the dna isolation protocol differ for the plant and animal cells?

Jessi consumes a diet of 1920 total kcalories that has 80 g of fat. what percent of jessi's diet comes from fat? (give answer to the appropriate reporting digit. only give the value. do not include the term percent or its abbreviation.)

Scientists break down evolution into catogories

The process of sediments being compacted and cemented to form sedimentary rocks is called A. metamorphism. B. deposition C. crystallization D. lithification

What is presumptive identification of a microorganism?

Which statement best describes the climate of a city? Select one: The average annual temperature of Austin, TX is 68.5°E San Antonio, Texas had a high temperature of 102°F today. Dallas, Texas had 8.6 centimeters of rain today.