SCIENCE 10
UNIT A: ENERGY AND MATTER IN CHEMICAL CHANGE
Unit Focus Questions
- How did the cell theory replace the concept of “spontaneous generation” and revolutionize the study of life sciences?
- How do single-celled organisms carry out life functions?
- How do plants use specialized cells and processes to accomplish the same functions as a single cell, but on a larger scale?
- How does imaging technology further our understanding of the structure and function of cells?
Chapter B1.0 Investigating the energy flow in technological systems requires and understanding of motion, work, and energy
Key Concepts
- One-dimensional Motion
- Work
Learning Outcomes
- Define, compare and contrast scalar and vector quantities
- Describe displacement and velocity quantitatively
- Define acceleration quantitatively as a change in velocity during a time interval
- Explain that, in the absence of resistive forces, motion at constant speed requires no energy input.
- Recall from previous studies the operational definition for force as a push or pull, and work as energy expended when the speed of an object is increased or when an object is moved against the influence of an opposing force.
- Investigate and analyze one-dimensional scalar motion and work done on an object or system using algebraic and graphical techniques.
Unit C Menu |
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C1.1 A Window on a New World C1.2 Development of Cell Theory C1.3 Developments in Imaging Technology and Staining Techniques C1.4 Cell Research at the Molecular Level |
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C1.1 A Window on a New World
Early Microscopes and Microscopists
Microscopes were invented in 1595 by Hans and Zacharias Janssen. It was acompound microscope. Compound meaning more than one lens.Had the ability to magnify objects by a factor of 20 times. eg. 1 mm would look like 20 mm through the lens
Antoni van Leeuwenhoek used high quality single lens microscopes with a magnification of 250X. He observed single celled animals: bacteria, sperm and unicellular protozoa, and made detailed diagrams of each.
Improvements in Lens Technology
Single lens microscopes were initially better than compound (multiple lens) microscopes. Once higher quality lenses (achromatic) were used in compound microscopes, they became much more powerful than single lens microscopes.Cell theory
Robert Brown identified that the dot seen in a cell is the nucleus and is important for cell function.M.J. Schleiden observed that all plants were composed of cells and the nucleus was in fact the structure that is responsible for the development of the cell.
Shleiden's friend Theodor Schwann found the same cell structure made up animal cells and the cells also contained a nucleus.
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C1.2 Development of the Cell Theory
Spontaneous generation
The idea that life could emerge, without external interference, from non-living material. If you put out organic materials, living things would develop from the materials.Von Helmont's experiments to prove spontaneous generation
In the early 1600s Von Helmont did an experiment to verify spontaneous generation of life by putting wheat and cloth in a container in a field for a month. At the end of the month he found mice in the container and concluded that the wheat and cloth had turned into mice through spontaneous generation.- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Von Helmont's second experiment was to plan a willow tree in a pot. He carefully measured the mass of the dirt and the seed at the start. He then only added measured amounts of water to the pot for 5 years. At the end he measured the mass of the dirt (no change) and the mass of the tree (large increase). Von Helmont concluded that the extra mass of the tree (living) was the water (non-living) being changed into living matter which again supported spontaneous generation.
- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Redi's experiment to disprove spontaneous generation
In 1668 Francesco Redi challenged the idea that meat would spontaneously change into maggots. He split a piece of meat in pieces and placed each piece in a different jar. He put the lids on some jars, cloths over other jars and left the other jars open. After a period of time he observed that the open jars had maggots going on the meat and concluded that the flies had left the maggots on the meat, because the othe jars had no flies due to the coth or closed jars. This experiment disproved spontaneous generation because it showed that maggots (life) had to come from flies (life).- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Needhan experiment to prove spontaneous generation
In 1745 John Needhan knew that boiling broth would kill all microbes in the broth. He boiled broth and then sealed the containers. Over time the broth would turn cloudy indicating the presence of microbes. Needhan concluded that the broth (non-living) and changed into microbes (living).- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Spallzani's experiment to disprove spontanteous generation
Lazzaro Spallzani citicized Needham's experiment by pointing out that microbes from the air could have got into the broth after boiling but before it was sealed. To counter this Spallzani sealed the broth containers and boiled them, killing all microbes in the containers. The broth did not turn cloudy. However, he was criticized because the sealed containers would not allow air to get in, and air is necessary for life.- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Pasteur's experiment to disprove spontaneous generation
Louis Pasteur modified Spallzani's experiment to allow air in. He made a containter with a long S shaped neck. This allowed air in and out of the container but dust and microbes would settle in the curve. He boiled the broth and it stayed clear. He could then carefully tip the container so some broth touched the dust in the S neck and then the broth would turn cloudy which should the microbes came from the dust.This was considered a definitive experiment that showed spontaneous generation was not possible.
- What was the manipulated variable?
- What was the responding variable?
- What was a control variable?
Cell Theory
With the improvements in microscopes, in 1833 Robert Brown identified an important cell structure, the nucleus. Matthias Schleiden was studying plants and Theodor Schwann was studying animals. Together they found that both animals and plants were made of cells and the cells had nuclei.- All living things are made up of one or more cells and the materials produced by the cells.
- All life functions take place in cells, making them the smallest unit of life.
- All cells are produced from pre-existing cells through the process of cell division.
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C1.3 Developments in Imaging Technology and Staining Techniques
Contrast - The ability to see differences between structures due to differences in their capacity to absorb light.Resolution - Resolution or resolving power. The ability distinguish between two structures that are close together
Electron Microscope (EM) - A microscope that uses a beam of electrons to produce images of fine detail.
Scanning Electron Microscope (SEM) - An EM in which a three-dimensional image is formed by electrons bouncing off the surface of the specimen.
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C1.4 Cell Research at the Molecular Level
Gene Mapping - Genes are the genetic information that dictates what you look like and your characteristics.Green Fluorescent Protein (GFP) Technology and Genetic Studies - GFP is a genetic protein that makes jellyfish glow in UV light. GFP is inserted into a organism to make certain parts of the organism glow. It helps scientists identify how proteins work in that organism.