Lignin
It is a complex organic polymer that form an important structural materials in the support system of vascular plants and can also be found in some algae. This is an important molecule in the structural composition of cell wall, such as in wood and bark. This also allow woods and barks to have strong, rigid which allows them to no break easily. Lignin can also be found inserted in the cell wall of this plants.
Answer:
D. A bicycle rusting.
Explanation:
A. is incorrect because tearing a piece of paper is a physical change, not a chemical change.
B. is incorrect because we are just heating up the object. That only changes how fast the particles are moving and the change in state of matter.
C. is incorrect because we are adding heat to change a state of matter (from solid to liquid) and it is a physical change.
Therefore, only D. is the correct answer. Iron rusts, and when it does, it chemically changes into an iron oxide (rust).
Answer:endocrine gland
Explanation: these are duct less glands
Answer is D
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