Grade 10 Life Sciences: Cell Structure, Membranes notes
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Course
Life Sciences
Institution
10th Grade
Grade 10 Life Sciences notes covering key topics such as the structure and function of the plant cell wall, including the primary and secondary cell walls, middle lamella, pits, and plasmodesmata. It also delves into the cell membrane, explaining the fluid mosaic model, the movement of substances, ...
• Atoms: The smallest particle of an element. Each atom consists of protons,
neutrons, and electrons.
• Molecules: Formed when two or more atoms bond together. For example:
o Oxygen molecule (O₂) = two oxygen atoms.
o Water molecule (H₂O) = two hydrogen atoms + one oxygen atom.
Compounds: Molecules formed by atoms of different elements.
• Example: Water (H₂O) is a compound formed by two hydrogen atoms and one oxygen
atom.
Important Elements in Living Organisms:
• Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sodium
(Na), Potassium (K), Calcium (Ca), Sulfur (S), Iodine (I), Iron (Fe), Magnesium
(Mg).
Carbon is a key element in organic molecules.
Oxygen and hydrogen are essential for water and energy production.
Nitrogen is crucial for amino acids and DNA.
Key Compounds in Cells:
1. Carbohydrates: Source of energy.
2. Lipids (Fats): Energy storage, cell membrane structure.
3. Proteins: Enzymes, structural components, and hormones.
4. Nucleic Acids (DNA and RNA): Genetic material.
5. Water (H₂O): Medium for chemical reactions, temperature regulation.
Types of Chemical Compounds:
1. Inorganic Compounds: Do not contain carbon (e.g., water and mineral salts).
o Carbon Dioxide (CO₂): An exception (contains carbon but is inorganic).
2. Organic Compounds: Contain carbon (e.g., carbohydrates, proteins, lipids, nucleic
acids).
, 1.1.1 Water
Properties of Water:
• Temperature Regulation: Water regulates body temperature through sweating.
Evaporation removes heat, cooling the body.
• Body Composition: 65% of the human body is water. Water is a crucial part of all
biological processes.
• Transport Medium: Transports food through the alimentary canal, and nutrients and
corpuscles (blood cells) in the bloodstream.
• Lubricating Agent: Provides lubrication in bodily fluids like saliva, tears, and vaginal
fluids.
• Solvent for Biological Chemicals: Many substances dissolve in water, making it
essential for biochemical reactions.
• Chemical Reaction Medium: In the cytoplasm of cells, water facilitates chemical
reactions necessary for life.
• Hydrolysis Reactions: Water is required to break down large molecules into smaller
ones (e.g., during digestion).
Water Molecule Structure:
• Polar Molecule: Water has partial positive charges on the hydrogen atoms and a
partial negative charge on the oxygen atom, allowing it to interact with other polar
molecules and ions.
Minerals
Importance of Minerals:
❖ Minerals are inorganic substances required for various biological functions.
❖ Plants absorb minerals from the soil, and animals obtain them from food.
❖ Essential for metabolic reactions and maintaining bodily functions.
Types of Minerals:
❖ Macroelements: Needed in large amounts (e.g., calcium, potassium, phosphorus).
❖ Microelements: Needed in trace amounts (e.g., iron, zinc, iodine).
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