Answer:
Fibrous
Explanation:
Proteins are assembled according to their functions. Fibrous proteins usually provide protection and support to cells. They are made up of polypeptides that have elongated shape and assembles in large cables or threads. These proteins are differentiated from globular proteins by their globular form and repeated units of amino acids.
For example the fibrous proteins involved in horns, hair and nails is alpha-keratin. Elastin found in skin and ligament is also a fibrous protein. Collagen includes collagen fibrils that have tensile strength of steel is also a fibrous protein found in cartilages and bones.
Albert, a student researcher, varies the amount of food given to rats in an experiment to measure the effect on their learning behavior. In albert's study, the amount of food given is the independent variable.
An independent variable is under the control of the experimenter. Independent variable does not depend on the other variables involved in the experiment. Since the amount of food is varied, it is not depending on other variables like size of mice, weight, etc.
I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
It is a to my knowledge, but I will give an update when i find out
