What is the primary function of xylem in plants?

Transport of water and minerals

What is the role of enzymes in biological reactions?

To speed up reactions by lowering activation energy

Chemicals of Life: A Biology Cheat Sheet

Life's processes are driven by the chemical reactions and structures of key biomolecules: carbohydrates, proteins, and fats, all of which are built from simpler monomers and play vital roles in energy, structure, and function.

Core Principles

Condensation reactions join monomers to form polymers by removing water, while hydrolysis reactions break polymers down by adding water.
Carbohydrates are simple sugars (monosaccharides) or complex chains (polysaccharides) providing energy and structural components.
Proteins, made of amino acids, are essential for building muscles, energy, antibodies, and cellular repair.
Fats are a secondary energy source, protect organs, insulate, and help dissolve vitamins.
DNA's double helix structure, composed of sugar-phosphate backbones and base pairs (A-T, G-C), carries genetic information.
Enzymes, biological catalysts made of protein, speed up reactions by lowering activation energy and are specific to their substrates.
Plant nutrition involves specialized leaf structures like stomata for gas exchange and xylem/phloem for transport.
Photosynthesis, driven by light, CO2, and water, produces glucose and oxygen, with its rate limited by these factors, temperature, and stomatal opening.
Water uptake in plants occurs via osmosis through root hairs into the xylem, which transports water and minerals.
Translocation moves sucrose and amino acids through the phloem from source to sink.
Transpiration is the loss of water from stomata, creating a pull that draws water up through the xylem.
Human nutrition requires a balanced diet of carbohydrates, proteins, fats, vitamins, and water for optimal health.
Digestion breaks down food physically and chemically, followed by absorption of nutrients into the bloodstream and assimilation into cells.
The digestive system, from mouth to anus, utilizes mechanical and chemical processes aided by enzymes and specialized organs.

Action Steps

Identify monomers (e.g., glucose, amino acids, fatty acids) to understand polymer formation.
Recognize condensation reactions as building blocks and hydrolysis as breakdown.
Test food for starch using Iodine (blue-black for positive) and for reducing sugars using Benedict's solution (green-blue-red for positive).
Test food for protein using Biuret test (blue to violet for positive).
Test for fats using the emulsion test (transparent to cloudy/milky for positive).
Understand that enzymes are specific and denature at high temperatures or extreme pH.
Observe how limiting factors (CO2, light, temperature) affect the rate of photosynthesis.
Recognize the role of xylem in water transport and phloem in sucrose transport.
Ensure a balanced diet including all macronutrients and micronutrients for proper human nutrition.
Understand the five processes of digestion: ingestion, digestion, absorption, assimilation, and egestion.

Key Terms

Condensation: A process where two small molecules join to form a larger molecule by removing water.
Hydrolysis: A process where a large molecule is split into smaller molecules by adding water.
Monomer: A small molecule that can join with other molecules to form a polymer (e.g., glucose, amino acid).
Polymer: A large molecule made up of repeating structural units (monomers) linked together (e.g., starch, protein).
Monosaccharide: A simple sugar, the basic unit of carbohydrates (e.g., glucose, fructose, galactose).
Disaccharide: A sugar formed from two monosaccharides (e.g., maltose, sucrose, lactose).
Polysaccharide: A complex carbohydrate made of many monosaccharide units (e.g., starch, glycogen, cellulose).
Amino Acid: The monomer unit of proteins.
DNA: Deoxyribonucleic Acid, a molecule that carries genetic instructions.
Enzyme: A biological catalyst, usually a protein, that speeds up chemical reactions.
Stomata: Pores on plant leaves that control gas exchange and transpiration.
Xylem: Plant tissue that transports water and minerals from roots to leaves.
Phloem: Plant tissue that transports sugars (sucrose) and amino acids from source to sink.
Photosynthesis: The process by which green plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen.
Transpiration: The loss of water vapor from plants, primarily through stomata.
Digestion: The process of breaking down food into smaller molecules that can be absorbed.
Absorption: The process by which digested nutrients pass through the intestinal wall into the bloodstream or lymph.
Assimilation: The process by which absorbed nutrients are incorporated into the body's cells and tissues.

Real World Examples

Two glucose molecules combine.: This is a condensation reaction forming maltose and releasing water.
A starch molecule is broken down.: This is a hydrolysis reaction, where water is added to break the bonds between glucose units.
A plant leaf has limited CO2 available.: CO2 becomes a limiting factor for photosynthesis, reducing the rate of glucose production.
A person eats a meal high in carbohydrates.: The carbohydrates are digested into glucose, absorbed, and used for energy or stored as glycogen.
A plant is in a very dry environment.: Stomata may close to conserve water, which can also limit CO2 intake and thus photosynthesis.

Timeline

During digestion: Condensation reactions build polymers from monomers.
During digestion: Hydrolysis reactions break polymers into monomers.
During photosynthesis: Light energy is used to convert CO2 and water into glucose.
After absorption: Glucose is assimilated into cells for energy or converted to glycogen for storage.
During plant transport: Xylem transports water and minerals upwards; phloem transports sucrose and amino acids from source to sink.

People

Unknown: Author of the notes

Quiz

What process joins two small molecules to make a large one by removing water?: Condensation
Which molecule is the monomer for proteins?: Amino Acid
What is the primary function of xylem in plants?: Transport of water and minerals
Which test is used to detect the presence of reducing sugars?: Benedict's test
What is the role of enzymes in biological reactions?: To speed up reactions by lowering activation energy