The structure that contains the male gametophyte is called the
A. pollen grain.
B. embryo.
C. seed coat.
D. cone.
Ans: A. pollen grain.
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When lipids, phosphates, carbohydrates and RNA were placed on clay, a liposome was formed. Why was the clay an important surface for liposome formation and how is RNA associated with the liposome?
A. Clay acts as a catalyst for the formation of a liposome that can grow and divide. The RNA molecules are enclosed inside the lipid bilayer. B. Clay causes anions to stick together, while the cations are pulled from the carbohydrates. This chemical reaction causes the formation of a carbohydrate- and RNA-based membrane. C. The clay surface provides a nutritional media for the growing and dividing liposome. RNA is incorporated into the liposome as a transmembrane catalyst. D. The positively charged clay surface reacts with the negatively charged phospholipids to create a clay ball. RNA molecules adhere to the outside surface of the clay ball. E. Phospholipds react chemically with the negatively charged clay surface, creating an impermeable membrane. The RNA molecules WOULD be incorporated as part of this membrane.
Which of the following class of antibody is primarily found in external secretions?
A. IgA B. IgD C. IgG D. IgE
Tears and saliva contain the enzyme dermicidin, which is effective in preventing bacteria from entering the human body
Indicate whether the statement is true or false
Which animal has a double digestive opening?
a. coral b. a flatworm c. an earthworm d. a hydra