Unit 1

Cycling of Matter in Living Systems


  Conclusion

Plants are fascinating examples of multicellular organisms.



AC.1 Structure of a leaf
The systems found in multicellular organisms are made up of organs that are made up of tissues that are in turn made up of cells. Without the cell, multicellular organisms could not survive, as the cells help the multicellular organism perform the basic functions of life.

In this unit, we studied cells and their functions. We looked at both plant and animal cells as single-celled organisms and determined how they performed the basic life functions. We studied the development of the cell theory and how microscopes played a huge part in this development. We also learned how microscopic research and knowledge about the cell membrane has impacted society.

Finally, we looked at plants as an example of a multicellular organism and we studied how cells can take on specialized functions in order to work together.

In the next unit, you will study matter and energy in chemistry.
AC.2 Animal vs. plant cell

  Review Questions

Complete the following review questions to check your understanding of the concepts you have learned. Make sure you write complete answers to the review questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. How was the theory of spontaneous generation disproved?
The theory of spontaneous generation was disproved through experimentation. Francesco Redi did an experiment using three jars and raw meat that showed flies only appeared on the raw meat when the meat was in a jar open to the air. Then Louis Pasteur performed his S-bend flask experiment where he stopped microorganisms from growing in broth by first boiling it and then leaving it in an S-bend flask. This showed that microorganisms only arose from other microorganisms and disproved spontaneous generation.

  1. Name the three points of the cell theory.
    1. All living things are made up of one or more cells and the materials produced by these cells.
    2. All life functions take place in cells, making them the smallest unit of life.
    3. All cells are produced from pre-existing cells through the process of cell division.

  1. Why are microscopes important to the study of the cell?
Microscopes allow us to see cells in order to study them. Without microscopes, we would only be able to guess what cells look like or what is inside them. Some microscopes even allow us to observe living cells so we can observe how they perform their functions.

  1. Complete the following table around the cell organelles.

Organelle Function
cell membrane

nucleus
lysosome
vacuole
mitochondria
endoplasmic reticulum
Gogli apparatus
ribosomes
chloroplast
cell wall

Organelle Function
cell membrane protective barrier around the cell
nucleus directs the cell’s processes, houses DNA
lysosome digests the particles brought into the cell
vacuole used for storing and moving particles around in the cell
mitochondria
  • makes energy from glucose for the cell to use
  • where cellular respiration takes place
endoplasmic reticulum
  • makes proteins (rough ER)
  • makes oils and lipids (smooth ER)
Golgi apparatus
takes the proteins, oils, and lipids made in the ER and packages them into vesicles for transport around and out of the cell
ribosomes help to create proteins
chloroplast
  • where photosynthesis takes place
  • produces glucose and oxygen
  • only present in plant cells
cell wall
  • protective barrier around the cell,
  • also provides structure to the shape of the cell
  • only present in plant cells


  1. What are the similarities and differences between plant and animal cells?
Your answer should include the following:

Similarities:
  • Plant and animal cells contain the same organelles, except for cell walls and chloroplasts.
  • Both plant and animal cells make specialized compounds according to their functions.
  • Both plant and animal cells contain DNA.
  • Both plant and animal cells are made of carbon, nitrogen, hydrogen, and oxygen.
  • Both plant and animal cells require water and use lipids, proteins, carbohydrates, and nucleic acids.

Differences:
  • Only plant cells contain chloroplasts and cell walls.
  • Only plant cells make chlorophyll.
  • Only animal cells make hemoglobin.
  • Plant cells store energy as starch and oils, while animal cells store energy as sugars and fats.
  • Plant cells have a large central vacuole, while animal cells have small vacuoles.

  1. Label each of these images with the type of cell transport being pictured.

1
©ADLC
AC.3 Cell Transport 1

2
©ADLC
AC.4 Cell Transport 2

3

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AC.5 Cell Transport 3

4
AC.6 Cell Transport 4

5
AC.7 Cell Transport 5

Cell transport 1—facilitated diffusion using a protein channel.
Cell transport 2—diffusion.
Cell transport 3—osmosis.
Cell transport 4—active transport.
Cell transport 5—endocytosis.

  1. How does the surface area to volume ratio limit cell size?
If the cell’s volume is too big when compared to the surface area, the cell will struggle with transporting into the cell the materials it needs. The cell membrane acts as the doorway to the cell, and if it is too small compared to the volume of the cell, there will not be enough room for all the materials to move into the cell at the rate needed. This is similar to a large crowd of people trying to all get through one doorway.

  1. Give one example of how microscopic research or knowledge of the cell membrane has benefited society.
Any answer from the textbook, the course content, or your own research is a great answer. Some examples include: HIV or cancer treatment, peritoneal dialysis, stem cell research, gene mapping, reverse osmosis, cell communication, and liposomes.

  1. How are the cells in a multicellular organism organized?
Cells → tissues → organs → systems

  1. Label the following leaf diagram with all the visible parts.


AC.8 Cell structure of a leaf



AC.9 Cell structure of a leaf


  1. Describe how the stomata and guard cells function.
Your answer should include the following:

  • When sunlight hits the two guard cells surrounding a stoma, it actively transports potassium ions into itself.
  • This causes water to flow into the guard cells through osmosis.
  • As the cell becomes turgid, it changes shape to become more crescent-like.
    • This happens because the membrane surrounding the stoma is thicker, so the pressure from the water causes the guard cell to push out away from the stoma.
  • This opens the stoma.
  • As the light disappears, or there is not enough water left, the potassium ions are transported out of the guard cells by active transport.
  • Once again, the water follows through osmosis.
  • The guard cells go back to their original shape, and the stoma is closed.

    1. Explain how water is transported from the roots of the plant to the leaves.
    Water is transported from the roots to the leaves through root pressure and transpiration pull. The minerals in the soil are actively transported into the roots, and water follows by osmosis. As the water pressure in the roots increases, the water molecules are pushed farther and farther up the root system toward the stem. This is root pressure. As water leaves the leaves of a plant through transpiration, the rest of the water molecules are pulled up the stem into the leaves. This is done through the water properties of cohesion and adhesion. The water particles are attracted to each other and the walls of the xylem, so as one molecule leaves, the attraction force pulls the next molecule into place. This is called transpiration pull.

    1. How are gravitropism and phototropism similar? How are they different?
    Gravitropism and phototropism are both control systems in plants. They are the plant’s response to stimuli in their environment, telling them which way to grow. Phototropism is the plant’s response to sunlight. The stem and leaves grow toward the sunlight (positive phototropism) and the roots grow away from sunlight (negative phototropism).

    Gravitropism is the plant’s response to gravity. The stem and leaves grow against gravity (negative gravitropism), and the roots grow with gravity (positive gravitropism).


      Unit A Project

    Complete the following Unit A Project to wrap up this unit. You will find a project like this one at the end of every unit in the course. These projects are meant to help you put the concepts you have learned in the unit together. There are two options for this project. Please choose only one to complete. Once you have chosen the one you wish to complete, please make sure you read the instructions carefully and follow the rubric. Make sure you ask your teacher if you have any questions.