Answer:In old stems the epidermal layer, cortex, and primary phloem become separated from the inner tissues by thicker formations of cork. Due to the thickening cork layer these cells die because they do not receive water and nutrients. This dead layer is the rough corky bark that forms around tree trunks and other stems.
Explanation: wikipedia.
Coral reefs form in warm, shallow waters.
Variations can be genetic or environmental, the traits are passed from one generation to other generation of snail is from from both parents to offspring and through the environment.
The correct answer is C.
Explanation:
Genetic variation in an organism is passed to the offspring by its parents.
environmental variation is the the result of different environment with which individual adapt.
Natural selection is a process in which a suitable trait which is well adapted to the environment is passed on tho future generations.
Genetic variation is the change in DNA or gene of the individual trait. The tree snails having different pattern in their shells is due to the habitat they are living in.
The snails which have well adapted to the environment are able to reproduce and pass on the traits to their progeny. The variation is due to the traits passed from parents through the environment also.
The best answer to the question above would be letter d. The sentence presented which is 'Researchers helped further the biological perspective when they demonstrated that electrical stimulation of the brain could evoke emotional responses in animals.' demonstrates how new discoveries can influence perspectives.
