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Science 10 - Unit 3: Cycling of Matter in Living Systems
Section 3 – Plants are multicellular organisms with specialized structures
3.1: Cells, Tissues, and Systems
The cells of all organisms must acquire nutrients and remove wastes, along with other
essential functions (reproduction etc). Recall, the surface area to volume ratio of a cell
affects the rate of diffusion into/out of a cell. The larger the cell, the lower the SA/vol
and the lower the rate of diffusion. This limits the size of cells possible (along with the
size of organism possible).
So how do larger organisms work?
As organisms become larger and more complex, they tend to exist as multicellular
organisms – having two or more cells (YOU contain trillions of cells). In order to meet
the requirements of all the cells in a multicellular organism, cells must “cooperate” with
one-another by specializing their function. Many cells performing the same task make up
tissues. A number of tissues grouped together to perform similar functions make up
organs. Multicellular organisms depend on this specialization to carry out life processes.
Turn to page 297 of the textbook and read the introduction to “Cells, Tissues, and
Systems” as well as the information in “Plant Structure” on pages 297 to 300.
Questions:
1. What are the advantages of the multicellular organism?
2. Write the terms system, tissue, and organ in order of increasing complexity.
3. Name one tissue, one organ, and one system in the human body.
4. What does the shoot system of a plant consist of?
5. What does the root system of a plant consist of?
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6. Is a tuber part of the shoot system or the root system?
7. What are meristems?
8. Name and describe the three main types of plant tissue.
Vascular tissue is a general name for two types of parallel tube cells that are bundled
together. The two types of tissue are xylem tissue and phloem tissue. You can see xylem
and phloem tissues in Figure C3.7 on page 300 of the textbook.
9. a. What is the purpose of xylem tissue and phloem tissue?
b. Compare the structure of xylem tissue to the structure of phloem tissue.
10. What are companion cells?
11. What is a vascular bundle?
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After a period of time, plant cells that were part of the meristem become specialized for
a particular function and make only products needed for that function. Some specialized
cells are root hairs, xylem and phloem cells, guard cells, and stomata.
Read the information in “Specialization in Plant Cells” on pages 301 and 302 of the
textbook.
12. State the purpose of each of the following parts of a plant.
a. root hairs
b. dermal cells
c. guard cells
d. stomata
Looking back: Answer question 5 of “Check and Reflect” on page 302 of the textbook.
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