The four basic needs of all living things are sunlight, air, water and food. The survival of living organisms also depends on limiting factors such as soils, temperature and physical barriers. These factors, which are specific to their environments, often limit where certain species can live.
Sunlight is considered the most important need since it provides all living things with heat and energy. Energy also comes from food in the form of nutrients. Water serves as a medium for cells and tissues and as a living environment for certain plants and animals. Air supplies essential gases, such as oxygen and carbon dioxide.Learn More
The organelles that contain digestive enzymes are called lysosomes. These cellular structures primarily function for the breakdown of complex molecular substances, such as carbohydrates, lipids, proteins and nucleic acids.Full Answer >
Nucleotides are the monomer of DNA. They are made of a 5-carbon sugar (deoxyribose), a phosphate group, and a nitrogenous base bound to the sugar. The four different types of nucleotides are adenine (A), thymine (T), guanine (G) and cytosine (C).Full Answer >
Speciation, commonly known as macroevolution, is supported by several lines of evidence, including direct observation, genetic mapping and the fossil record. Several populations have been observed in the act of splitting into new species. Comparison of genomic sequences between species are most easily explained as a result of recent common ancestry and an extensive fossil record has yielded numerous transitional fossils.Full Answer >
Genetic variation is important to evolution because it helps to maintain the health of a population by constituting alleles that may be useful in overcoming stresses such as diseases and pests. Without genetic variation, some of the fundamental mechanisms of evolutionary changes would not operate.Full Answer >