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This section is all about the plant cell and what plants need for growth. There is also a bit of an intro to photosynthesis but that will be covered in detail in the next section. We start out with understanding plant cells with a focus on what makes them different from animal cells. For example - a cell wall and chloroplasts are extremely notable! We then dive into a history of how we came to know what plants need and how they grow. It seems obvious now but it was not always so! We finish up with some great time lapse videos showing plant growth in action. Plants do some amazing things - just not at the same speed that we live in!
Plant Cells - what makes them special and what they contain
Plant Cells - what makes them special and what they contain
Crash Course - the Plant Cell (differences from animal cell)
Nucleus (animal and plants)
Organelles (animal and plants)
Cytoplasm (animal and plants)
Rigid Cell Wall (gives structure to leaves, roots, stems)
Cellulose - we cannot digest this - look to ruminants & bacteria
Lignin
Organelles formed via endosymbiosis
Mitochondria
Chloroplasts (a plastid)
Central Vacuole - rigidity controlled by water
Turgor pressure (cells made turgid)
Reinforces the plant
Chloroplasts moving within plant cells (notice cell wall) possibly to become properly oriented to light. This is just a quick and cool video for you to see real life chloroplasts moving around in a dynamic plant cell!
This is an idealized diagram of the plant cell (not to scale). This is meant to be an aid to what is discussed in the Crash Course video above.
Microscope Picture of Plant Cell
This is here to get you a non-idealized look at the real plant cell. Again it is here to reinforce the learning from the Crash Course video
Diagram of Plant Cell Wall Structure
This diagram of the plant cell wall is just to give you an idea of how rigid molecules like cellulose and hemicellulose give a plant cell its rigid cell wall.
what a plant needs to grow, growth behavior, and intro to photosynthesis
what a plant needs to grow, growth behavior, and intro to photosynthesis
Botany: A Blooming History (Part 2) - How a Plant Grows and Introduction to Photosynthesis
Jean-Baptiste van Helmont
experiment detailing mass of plant & mass of soil it is growing in - plants don't eat soil! - conclusion - plants add mass and grow by drinking water (incorrect - weight is added by carbon not water)
Jan Ingenhousz
experiment with submerged leaves in a jar - accidental exposure to sunlight leads to bubbles of gas (later found to be oxygen) - experiment repeated with many plants - plants need sunlight!
Julius von Sachs
wrote treatise on plant growth
experiment to figure out how sunlight plays a role in the production of starch - strips green color - iodine applied and starch is turned black - used on plants with differing exposure to sunlight - sunlight is used to make starch!
used microscope to see chloroplasts within plant cells
Sachs's method of staying awake to get work done...cocaine
Plants produce sugar which is stored as starch - this is how plants grow
Stomata - openings through which plants take in carbon dioxide for photosynthesis
Andrew Benson & Melvin Calvin
experiment - How do plants use carbon dioxide to fuel their growth? - use of cyclotron (particle accelerator) to produce radioactive carbon atoms - this provides an isotopic label that allows you to follow carbon as it moves through a plant - chromatogram shows which compounds (i.e. sugars) contained the radioactive carbon - demonstrates HOW plants use carbon from the atmosphere to grow!
Calvin Cycle (now called Calvin-Benson Cycle)
Feud between Calvin & Benson
Manipulating photosynthesis for food production
adjusting light timing in a greenhouse allows peppers to grow to maturation
carbon dioxide is elevated in greenhouses (harvested from factories) to increase fruit yields and sugars in tomatoes
Synthetic Photosynthesis could provide us with oxygen and hydrogen gases for fuel - this could also draw down carbon dioxide in the atmosphere
Photosynthesis and seasonal variation on a global scale
half of photosynthesis happens in oceans
plants are significant drivers of Earth's atmospheric constituents
Really Cool Time-lapse demonstrating how plants sense which way is up by actually sensing gravity itself
Really Cool Time-lapse demonstrating how plants sense where light is grow towards it.
Really Cool Time-lapse demonstrating the process of growth and development from a seed.
Really Cool Time-lapse demonstrating the process of growth and development from a seed.
Really Cool Time-lapse demonstrating the process of growth and development from a seed.
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