Video Transcript
Which of the following best defines
a tissue? (A) A group of different cells that
work together to carry out multiple different functions. (B) A group of similar cells that
work together to carry out a particular function. (C) A group of organs that work
together to perform the same function. (D) Multiple different organs that
carry out different functions. (E) A mass of cells that are bound
together by membranes.
This question is asking us about
tissues, so what exactly is a tissue? Tissues are part of the
hierarchical organization of multicellular organisms. A hierarchical organization is when
the components of something large and complex can be divided into groups based on
their common traits. In a multicellular organism, such
as humans, we are made up of organ systems, which are made up of organs, which are
made up of tissues, which are made up of cells, and so on.
Since organs are made up of
tissues, we can already exclude answer choice (C), a group of organs that work
together to perform the same function. And we can also eliminate answer
choice (D), multiple different organs that carry out different functions. We can use this knowledge of organs
being made up of tissues to find the definition of a tissue.
Let’s look at some of the tissues
that make up the organ the lungs. One group of similar cells that
together cushion the lungs is known as pleural tissue. Another tissue type, the connective
tissue, is composed of many different types of cells. However, the most common of these
are called fibroblasts, and these groups of cells work together to provide structure
and support in the lungs. Another type of tissue is
epithelial tissue, and this is very important for lining the surfaces of different
organs. It is found in most organs,
including the brain, the lungs, and the heart. Epithelial tissue also lines
different cavities that house these organs. All of these cells work together to
serve a particular function: to breathe and exhale air.
Now let’s go over the remaining
answer choices to choose the one that best defines a tissue. Answer choice (A) is incorrect
because tissues are made up of cells that carry out similar and specific functions,
not different functions. Answer choice (B) seems to be
correct because a tissue is made up of cells that work together to carry out a
particular function. But let’s first eliminate the last
option before making our final decision. Answer choice (E) is partially
correct, because a tissue is made up of cells that are bound together. However, this is not the best
definition.
Therefore, the answer choice that
best defines a tissue is given by answer choice (B): a group of similar cells that
work together to carry out a particular function.
