Biological systems examples that can be found during a nature walk, such as cellular respiration

How does pregnancy begin? a) a placenta forms in the uterus b) a sperm reaches an egg in the fallopian tubec) the blastocyst differentiates into two cell types d) contractions begin in the uterine wallapex

(99 points) be serious! how do farts work? how do you fart without it stinking? serious answers only

What is usually (but not always) related to the metabolic processes of living organisms in its organic form?