Explain the fully developed (Bisporic embryo sac and Tetrasporic embryo sac ) types of embryo sac? in plant​

The variation among individuals, on which natural selection acts

If we assume that, in the african savanna, rainfall and the amount of grass is plentiful, what other factor would best explain a reduced antelope population?

Cancer cells spread to other parts of the body by entering the bloodstream. which of the following organs could prevent a cancer cell in the bloodstream from spreading, and why? a. the spleen, because it releases lymphocytes into the blood b. the peyer's patches, because they release lymphocytes into the blood c. the lymph nodes, because they release lymph into the blood d. the thymus, because it releases lymph into the blood