C. by observing them in their habitats
Ex: The Galapagos Islands. Darwin went their to study the flora and fauna in their natural habitat.
There have been 5 Mass Extinctions throughout Earth's history.
Answer:
I believe the answer is C
Explanation:
In many plant cells there is a single large central vacuole filled with liquid, pressure of the central vacuole allows plants to support heavy structures such as leaves and flowers.
Mammalian fertilization comprises sperm migration through the female reproductive tract, biochemical and morphological changes to sperm, and sperm-egg interaction in the oviduct. Recent gene knockout approaches in mice have revealed that many factors previously considered important for fertilization are largely dispensable, or if they are essential, they have an unexpected function. These results indicate that what has been observed in in vitro fertilization (IVF) differs significantly from what occurs during “physiological” fertilization. This Review focuses on the advantages of studying fertilization using gene-manipulated animals and highlights an emerging molecular mechanism of mammalian fertilization.
Answer: (SL) Semilunar Valves
Explanation:
