Ash, green, and red (Fraxinus spp.)âThe common. leaf spot and scorch on ash leaves is caused by the ash. anthracnose fungus, Gloeosporium aridum. Large areas of. infected leaves, especially along the edges, turn brown (Figure. 2). Premature leaf drop may occur.
How sperm and eggs develop precisely 23 chromosomes each. April 12, 2012. There are many tools that cells could use to separate DNA strands that cross over during meiosis. UC Davis researchers have identified the right tools for the job. Researchers at the University of California, Davis have discovered a key tool that helps sperm and eggs develop exactly 23 chromosomes each.
Sperm and egg cells are haploid cells, meaning they have half the number of chromosomes as all other cells in the body. Humans have 46 chromosomes, so human reproductive cells will have 23. Sperm and egg cells are haploid cells, meaning they have half the number of chromosomes as all other cells in the body.