However, human activities generate additional 'greenhouse gases'. Globally, atmospheric concentrations of two of the main greenhouse gases, carbon dioxide (CO2) and methane (CH4) have increased over the last 150 years. Agriculture has played a significant role in this-up to 35% of anthropogenic CH4 comes from animals and their wastes (Monteny et al. 2006).
sperm, sperm cell, spermatozoan, spermatozoon-the male reproductive cell; the male gamete; a sperm is mostly a nucleus surrounded by little other cellular material. egg cell, ovum-the female reproductive cell; the female gamete.
B. a somatic cell A muscle cell is a body' cell (somatic means body).A gamete is a haploid cell, such as an egg or a sperm, related to sexual reproduction, When an egg and a sperm fuse during fertilization they produce a diploid cell called a zygote.. a somatic cell A muscle cell is a body' cell (somatic means body).