Notes, summaries, assignments, exams, and problems for Biology

The Mechanism of Photosynthesis and Energy Conversion

Photosynthesis (pronounced FOH-tə-SINTH-ə-sis)^[1] is a system of biological processes by which photopigment-bearing autotrophic organisms, such as most plants, algae, and cyanobacteria, convert light energy—typically from sunlight—into the chemical energy necessary to fuel their metabolism. The term photosynthesis usually refers to oxygenic photosynthesis, a process that releases oxygen as a byproduct of water splitting.

Storing Chemical Energy and Maintaining the Atmosphere

Photosynthetic organisms store the converted chemical energy within the bonds of intracellular organic compounds (complex compounds containing carbon), typically carbohydrates like:

• Sugars (mainly glucose, fructose,

Electrical Fundamentals in Electrotherapy

Electrotherapy involves the use of electric currents for therapeutic purposes, commonly used in physical therapy and rehabilitation. Understanding the electrical fundamentals is crucial for effectively applying electrotherapy techniques.

Basic Concepts of Electricity

• Current (I): The flow of electric charge, measured in Amperes (A). It can be direct (DC) or alternating (AC).
• Voltage (V): The electrical potential difference that drives current flow, measured in Volts (V).
• Resistance (R): The opposition to current flow, measured in Ohms (Ω). According to Ohm's Law: V=I×R.

Types of Electric Currents in Electrotherapy

• Direct Current (DC): A unidirectional flow of electric charge, used in applications like iontophoresis.

Biology Concepts

Cellular Processes and Structure

• 1-A) Ev against abiogenesis.
• 3-C) Cannot maggots developed.
• 4-B) Life forms from non-living matter.
• 5-C) Cells contain organelles.
• 6-B) Move through phospholipid bilayer quickly.
• 7-A) Endocytosis.
• 8- Vacuole: 3, Nucleus: 7, Cytoplasm: 2, Rough ER: 4.
• 9- Synthesize lipids: 5, Convert glucose: 8, Convert sunlight: 1, Modify lipids: 6.
• 10-B) None.
• 11-D) Glucose and Oxygen.
• 12-C) Makes ATP.
• 13-B) Cells, tissues, systems.
• 14-C) Tissues.

Microscopy and Molecular Biology

• 15- 2) Internal structures: Transmission electron microscope (TEM), 3) 2 more lenses: Compound microscope, 4) 3D image: Scanning electron microscope (SEM), 5) Highest magnification: Scanning tunneling microscope (STM).
• 16-D) Mitch.
• 17-A) Starch molecule.

Steps in Root End Surgery

• Local anesthesia and hemostasis
• Management of soft tissue
• Management of hard tissue
• Surgical access (visual and operative)
• Access to root structure
• Periradicular curettage
• Root end resection
• Root end preparation
• Root end filling
• Soft tissue repositioning and suturing
• Post-surgical care

Root End Preparation

Preparing a cavity to receive root end filling.

According to Carr and Bentkover, this involves a Class I preparation at least 3mm into root dentin with walls parallel to and coincident with the anatomic outline of the pulp space.

Key requirements:

1. The apical 3mm of the root canal must be freshly cleaned and shaped.
2. The preparation must be parallel to and coincident with the anatomic outline of the pulp space.
3. Adequate retention form

Early Foundations and Key Milestones in Plant Tissue Culture

The science of plant tissue culture originates from the discovery of the cell, followed by the postulation of cell theory. In 1838, Schleiden and Schwann proposed that the cell is the basic structural unit of all living organisms. They envisioned that a cell is capable of autonomy and, therefore, it should be possible for each cell, if given the right environment, to regenerate into a whole plant. Based on this premise, in 1902, German physiologist Gottlieb Haberlandt for the first time attempted to culture isolated single palisade cells from leaves in Knop’s salt solution enriched with sucrose. The cells remained alive for up to one month, increased in size, accumulated starch,... Continue reading "Milestones in Plant Tissue Culture Development" »

Basement Membrane Structure & Function

Covering & Lining Epithelia

Knee Joint Anatomy and Function

This document provides a detailed look at the structure, mechanics, and common clinical aspects of the knee joint.

Type of Joint

• The knee is classified as a synovial hinge joint.
• It primarily allows flexion and extension.
• A small degree of medial/lateral rotation is possible when the knee is flexed.

Bones Involved

1. Femur (thigh bone)
2. Tibia (shin bone)
3. Patella (kneecap)

The fibula is nearby but does not participate in the primary knee joint articulation.

Articulating Surfaces

• The medial and lateral femoral condyles articulate with the tibial condyles.
• The patella articulates with the femoral trochlear groove.

Main Ligaments

1. Anterior Cruciate Ligament (ACL) – Prevents anterior displacement of the tibia relative to the femur.

Plasmids pBR322 and pUC18/19

pBR322

pBR322, developed in 1977, is a foundational plasmid in molecular biology. Key features include:

• Size: ~4,361 base pairs (bp)
• Origin of Replication: Allows independent replication within bacteria.
• Selection Markers:
  • ampR: Confers ampicillin resistance.
  • tetR: Confers tetracycline resistance.
• Cloning Sites: Multiple sites for inserting foreign DNA.
• Applications: Gene cloning, expression, and manipulation.

pUC18/19

pUC18/19, derived from pBR322 in the early 1980s, simplifies cloning. Key features include:

• Size: ~2,686 bp
• Origin of Replication: High-copy-number pMB1 ori for increased yield.
• Selection Marker:
  • lacZ: Beta-galactosidase gene; enables blue/white screening for insert identification.
• Cloning Sites: Multiple cloning

I. Reflex Activity: Definition and Physiology

• Reflex Definition: An involuntary, automatic response to a peripheral stimulus, involving either motor or secretory action.
• Function: Crucial for adaptation to internal and external changes.
• Dependence: Requires the integrity of the reflex arc; disruption at any level abolishes the reflex.

II. The Reflex Arc: Components

The reflex arc consists of five essential components:

1. Receptor Organ: Transforms a stimulus into nerve impulses.
2. Afferent Neuron: Conducts the impulse to the Central Nervous System (CNS).
3. Integration Center: Typically located in the spinal cord or brainstem; processes signals via synapses.
4. Efferent (Motor) Neuron: Sends the command from the CNS to the effector.
5. Effector: The muscle or gland

1. Brain Abscess

• Gross Morphology

  Localized area of liquefactive necrosis filled with yellow pus, surrounded by a thin fibrous capsule and edematous, inflamed brain tissue.

• Pathology

  Caused by hematogenous spread of bacterial infection, direct trauma, or contiguous spread (e.g., from sinuses). Represents focal suppurative inflammation of the brain.

2. Neurinoma (Schwannoma)

• Gross Morphology

  Well-circumscribed, encapsulated globoid mass with a soft, tan “fish-flesh” appearance, often with cysts or hemorrhage. Cut surface may show yellow patches.

• Pathology

  A benign tumor of Schwann cells, often seen in cranial nerves (especially CN VIII) and associated with neurofibromatosis type 2. Grows slowly and may compress adjacent structures.

3. Fibrinous