OCR Biology Module 2 Quiz

Introduction to OCR Biology Module 2

• Module 2 explores the interconnected biological processes within organisms, from cellular to organismal levels.
• It builds upon Module 1 and delves further into complex biological concepts.

Biological Molecules

• Carbohydrates include monosaccharides (e.g., glucose, fructose), disaccharides (e.g., sucrose, lactose), and polysaccharides (e.g., starch, glycogen, cellulose).
• Lipids are composed of fatty acids and glycerol, crucial for energy storage, insulation, and hormone production. Examples include triglycerides and phospholipids.
• Proteins, complex amino acid polymers, are essential for structural support, enzymes, transport, hormones, and defense mechanisms. Protein function is determined by its specific structure (primary, secondary, tertiary, and quaternary).
• Nucleic acids (DNA and RNA) are the genetic material, carrying instructions for protein synthesis. DNA stores genetic information; RNA plays roles in protein synthesis and other cellular processes.

Enzymes

• Enzymes are biological catalysts that accelerate biochemical reactions by lowering activation energy without being consumed.
• Enzymes have specific active sites that bind to specific substrates, forming enzyme-substrate complexes.
• Enzyme activity is affected by temperature, pH, and substrate concentration.
• Inhibitors, either competitive or non-competitive, affect enzyme reactions by binding to the active site.

Cell Respiration

• Cell respiration releases energy from glucose in stages, producing ATP.
• Glycolysis occurs in the cytoplasm, yielding a small amount of ATP.
• The Krebs cycle (citric acid cycle), in the mitochondrial matrix, produces further ATP, reducing NAD+ and FAD to NADH and FADH2 respectively.
• The electron transport chain (inner mitochondrial membrane) utilizes NADH and FADH2 high-energy electrons to generate a proton gradient, driving ATP synthesis via oxidative phosphorylation.

Photosynthesis

• Photosynthesis converts light energy into chemical energy (glucose) in chloroplasts.
• The process occurs within the thylakoid membranes.
• Light-dependent reactions capture light energy to produce ATP and NADPH, involving chlorophyll and other pigments.
• Light-independent reactions (Calvin cycle) use ATP and NADPH to fix carbon dioxide and synthesize glucose.

Nucleic Acids and Protein synthesis

• DNA's genetic information is transcribed into mRNA.
• mRNA carries the genetic code to ribosomes, where it's translated into a protein via codons on mRNA, anticodons on tRNA, and the functioning ribosome.
• Mutations in DNA sequence can lead to altered proteins.

Homeostasis

• Homeostasis maintains stable internal conditions, regulating factors like temperature, blood glucose, and water balance.
• Negative feedback mechanisms counteract deviations from the set point to maintain homeostasis.
• Positive feedback mechanisms amplify change, although less common.

Excretion and Osmoregulation

• Excretion removes metabolic waste products.
• Osmoregulation controls water and salt balance.
• Kidneys are crucial for excretion and osmoregulation, involving filtration, reabsorption, and secretion.

Transport in Plants

• Plants transport water, mineral ions, and sugars via specialized systems (xylem and phloem).
• Xylem moves water and mineral ions from roots to leaves.
• Phloem moves sugars from sources (leaves) to sinks (growing tissues, roots).

Transport in Humans

• Humans transport substances throughout their body through the circulatory system (heart, blood vessels, blood).
• Blood carries oxygen, nutrients, hormones, and waste products.
• The circulatory system maintains homeostasis.

Nervous System

• The nervous system allows communication between organism parts.
• Nerve impulses travel along neurons via action potentials.
• The nervous system rapidly responds to internal and external stimuli.

Endocrine System

• The endocrine system regulates numerous processes through hormones released into the bloodstream.
• Hormones act on target cells to induce specific responses, aiding in homeostasis.

Reproduction

• Asexual reproduction produces genetically identical offspring from one parent.
• Sexual reproduction involves two parents producing genetically diverse offspring through gamete formation, fertilization, and development.