For 17 the answer is d
for 18 the answer is b
Answer:
The cell wall is the outermost covering of plant cells. It is present outside the cell membrane and is tough, flexible and sometimes rigid in its texture. It is mainly composed of cellulose, long fibres of carbohydrates including hemicellulose, lignin and pectin.
The main functions of the cell wall are:
Protecting the cell against physical damage and invading pathogens.
Regulates and controls the direction of cell growth.
Providing the strength, structural support and maintaining the shape of the cell.
Functions as a storage unit by storing carbohydrates for use in plant growth, especially in seeds.
It allows entry of smaller molecules through it freely.
Explanation:
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<span>C. Blood components are continuously produced in the bone marrow.</span>
The greenhouse effect is the a. movement to reduce pesticides. b. hole in the ozone layer. c. increase in earth temperature due to trapped gases. d. decrease in earth temperature due to escaping gases
