GR10 SCIENCE EXAM: BIOLOGY

Below is a Knowt-ready study format. You can copy and paste this into Knowt. I organized it by unit, with clear headings, definitions, and important test points.

---

Science Exam Notes: Cells, Organelles, Cell Cycle, Cancer, Tissues, Body Systems, and Microscopes

1. Cell Theory

Discovery of Cells

• In 1665, English scientist Robert Hooke discovered cells while looking at a thin slice of cork.

• He described the cells as tiny boxes or a honeycomb.

• The boxes reminded him of monks’ living quarters, which were called cells.

• Hooke thought cells only existed in plants and fungi.

Anton van Leeuwenhoek

• In 1673, Anton van Leeuwenhoek used a handmade microscope to observe pond scum.

• He discovered single-celled organisms.

• He called them animalcules.

• He also observed blood cells from fish, birds, frogs, dogs, and humans.

• This helped scientists understand that cells are found in animals as well as plants.

Spontaneous Generation

• For about 150–200 years, very little progress was made in cell theory.

• This was partly because many people believed in spontaneous generation.

• Spontaneous generation is the old belief that living things could come from non-living matter.

• Examples:

• Mice from dirty clothes or corn husks

• Maggots from rotting meat

Pasteur’s Experiment

• In 1864, Louis Pasteur disproved spontaneous generation.

• He boiled nutrient broth in a swan-necked flask.

• Dust and microbes became trapped in the neck of the flask and could not reach the broth.

• No microorganisms grew in the broth.

• This showed that living things come from other living things, not from non-living matter.

Development of Cell Theory

• 1838: Matthias Schleiden

• Concluded that all plant parts are made of cells.

• 1839: Theodor Schwann

• Stated that all animal tissues are made of cells.

• 1858: Rudolf Virchow

• Concluded that cells must come from pre-existing cells.

Three Basic Parts of Cell Theory

1. All organisms are made of one or more cells.

2. The cell is the basic unit of life.

3. All cells come from pre-existing cells.

Modern Cell Theory

Modern cell theory adds more ideas:

• Cells contain hereditary information called DNA.

• DNA is passed from cell to cell during cell division.

• All cells have similar chemical composition and metabolic activities.

• Basic chemical and physiological functions happen inside cells.

• Cell activity depends on the activity of sub-cellular structures such as organelles, nucleus, and plasma membrane.

Uses of Cell Theory

Cell theory is important for:

• Disease research

• Medical research

• Cancer research

• Vaccines

• Cloning

• Stem cell research

---

2. Cell Types and Organelles

Prokaryotic Cells

• Prokaryotic cells are the simplest cells.

• Bacteria are prokaryotic.

• They have no membrane-bound organelles.

• They do not have a nucleus.

• Their DNA is circular and floats in the cytoplasm.

• Some bacteria have a capsule that helps them avoid the body’s immune system.

Eukaryotic Cells

• Eukaryotic cells are more complex than prokaryotic cells.

• They contain membrane-bound organelles.

• Their DNA is found inside a nucleus.

• Plant and animal cells are eukaryotic.