All of the statements regarding the history of life on Earth are true except: Group of answer choices a) The history of planet Earth includes alternations between colder periods ("icehouses") and warmer period ("greenhouses") on the surface of the planet b) The rise of more complex organisms such as eukaryotes has resulted in a reduction of diversity of more "primitive" organisms such as bacteria. c) There have been repeated incidents of mass extinction in the history of the planet in which species diversity has been reduced by 50% or more d) There is more oxygen in the atmosphere today than there was early in Earth history (4 billion years ago)

Long term exposure to waves can cause sunburns and skin cancer.

Diego conducted an experiment to find out what kind of ball bounces the highest when dropped from a five-foot platform. he used a golf ball, a tennis ball, and a soccer ball. he dropped each ball from the balcony once. diego recorded his observations after each drop. what can diego do to best improve the reliability of his results? a) drop each ball from the platform three more times b) record his observations in more than one unit c) write at least two scientific questions after the experiment is complete d) share his results with other people who have done similar experiments you for the !

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?