Explain how a person can be a carrier for a particular disease and yet not have the disease. is this true for all people who are carriers?

When analyzing tree rings, what do scientists assume a thin ring indicates?

Wich level of organization includes all the other levels or organizations

Parthenogenesis is a type of reproduction that does not require a mate. it’s rarely seen in birds and higher vertebrates. parthenogenesis involves the formation of a zygote. but this zygote is formed without fertilization. in parthenogenesis, in the absence of a male gamete, the ovum develops directly in the zygote.