Movement in and out of the cells & Biological molecules

Importance of Diffusion in Animals

Gas exchange (O2 and CO2) and absorption of dissolved food materials are carried out by diffusion.

Importance of Diffusion in Plants

CO2 and O2 exchange during photosynthesis; dissolved salts diffuse through root hair cells.

Definition of Diffusion

Net movement of particles from a region of higher concentration to lower concentration as a result of random movement.

Energy Source for Diffusion

The energy for diffusion comes from kinetic energy resulting from the random movement of particles.

Definition of Osmosis

Net movement of water molecules from areas of high water potential (dilute) to areas of lower water potential (concentrated) through a partially permeable membrane.

Effect of Distilled Water on Plant Cells

When placed in distilled water, plant cells swell and become turgid due to water entering the cell; the cell wall prevents bursting.

Effect of Salt Solution on Plant Cells

In a salt solution, water moves from the plant cell to the solution, making the cell plasmolyzed.

Factors Influencing Rate of Diffusion

1. Surface Area: Larger surface area allows faster diffusion.
2. Temperature: Higher temperature increases kinetic energy and diffusion rate.
3. Concentration Gradient: A steeper gradient enhances diffusion speed.
4. Distance: Thinner membranes facilitate faster diffusion.

Effects of Osmosis on Animal Cells in Water

Animal cells in water gain excess water through osmosis; if not expelled, cells may burst (hemolysis).

Effects of Osmosis on Animal Cells in Salt Solution

Animal cells in salt solution lose water and become shrunk (crenated).

Importance of Osmosis in Plants

Plants gain water through osmosis from soil to roots; lack of water causes cells to become flaccid, leading to wilting.

Definition of Active Transport

Movement of particles through cell membranes from lower concentration to higher concentration, using energy from respiration.

Role of Carrier Proteins in Active Transport

Carrier proteins pick up specific molecules and transport them through the cell membrane against the concentration gradient.

Importance of Active Transport in Human Body

Uptake of glucose by epithelial cells in small intestines and kidney tubules.

Importance of Active Transport in Plants

Uptake of ions from soil water by root hair cells.

General Structure of Proteins

Proteins contain carbon, oxygen, hydrogen, and nitrogen; they are long chains of amino acids with 20 different types.

Structure of Carbohydrates

Carbohydrates consist of carbon, oxygen, and hydrogen; they are long chains of simple sugars, such as glucose.

Basic Structure of Fats

Fats are made of triglycerides consisting of one glycerol molecule bonded with three fatty acid chains.

Structure of DNA Molecule

DNA consists of two strands of nucleotides forming a double helix, with four bases: adenine, cytosine, thymine, and guanine.

Iodine Solution Test for Starch

Add iodine solution to food sample; positive test turns blue-black.

Benedict's Solution Test for Reducing Sugars

Add Benedict's solution and heat; positive test shows orange or brick red.

Biuret Test for Proteins

Add biuret solution; positive test shows color change to violet/purple.

Ethnol Emulsion Test for Fats and Oils

Mix food sample with ethanol, then add cold water; positive test shows cloudy emulsion.

DCPIP Test for Vitamin C

Add DCPIP solution to test tube; positive test shows blue dye disappearing.