Which statement describes many of the structures involved in the first line of defense of the immune system? they have contact with the external environment. they are internal and contact the pathogen through blood. they produce b-cells in response to a pathogen. they produce t-cells in response to a pathogen.

Apea plant that is heterozygous for the tall phenotype can produce short offspring when self pollinating. which of the following explains why this occurs? a. segregation of allels b. condominance of traits c. polygenic expression of traits d. independent assortment of alleles

Hector is back from his morning run and is feeling light-headed because his energy is depleted which food item will provide him with a quick source of carbohydrates

(select all the correct choose each statement that is scientific. - the opinions of randomly selected participants in a survey prove the idea that global temperatures are not increasing on earth. - the universe's average temperature and rate of expansion support the idea that it began as one super-dense and hot mass 13.8 billion years ago. - ocean tides are caused by the uneven gravitational pulls of the moon and sun on different parts of earth. - human life is more valuable than other forms of life on earth because humans are more intelligent than other organisms.