Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

Muscular System

Muscle Characteristics

Involuntary. Located in the heart. Striated fibers are present inside longitudinal filaments called myofibrils. Muscle cells are made of two proteins: actin and myosin. Some form rhabdomyosarcoma.

Types of Muscles

• Long or Fusiform: (spindle-shaped)
• Flat or Planar: (e.g., diaphragm)
• Orbicular: (round body, e.g., orbicularis oculi)

Tendons join muscles to bones. Two muscles are involved in any movement: agonist (contracts) and antagonist (relaxes).

Skeletal System

3.2 - Bones

Functions

• Support the body and give it shape.
• Allow movement of various body parts.
• Protect internal organs (brain, lungs, etc.).
• Serve as the main repository of minerals (calcium, potassium, etc.).
• Some bones act as organs of blood cell production.

Cholera

Pathogen: Vibrio cholerae

Methods of Transmission:

• Foodborne
• Waterborne

Note: 3/4 of infected people may be asymptomatic carriers and pass large numbers of bacteria in their feces.

Global Distribution: Asia, Africa

Incubation Period: 1-5 days

Site of Action: Wall of the small intestine; secretes a toxin called choleragen

Clinical Features:

• Severe diarrhea
• Loss of water and salts
• Weakness

Note: Can be fatal if not treated within 24 hours.

Method of Diagnosis: Microscopic analysis of feces

Annual Incidence Worldwide: 5.5 million

Annual Mortality Worldwide: 120,000

Treatment: Antibiotics

Tuberculosis

Pathogen: Mycobacterium tuberculosis

Transmission:

• Airborne droplets
• Infected meat

Global Distribution: Worldwide

Incubation Period: A few weeks or months

Site of

Principles of Inheritance and Genetics

Basic Genetic Terminology

Diploid Organisms: Organisms possessing two sets of chromosomes and two alleles (forms) of each gene.

• Homozygous: Having two identical alleles for a trait (e.g., C^RC^R).
• Heterozygous: Having two different alleles for a trait (e.g., C^RC^r).

Mutation: A change in the amount or the chemical structure of DNA.

• Chromosomal Mutation: A difference in the number or structure of chromosomes.
• Gene Mutation: Changes within a gene (e.g., substitution, deletion, addition).

Phenotype: The observable characteristics (e.g., tall).

Genotype: The genetic makeup (e.g., Tt).

Gamete: A haploid reproductive cell (e.g., T & t).

Patterns of Inheritance

Codominance: Both alleles are expressed in the heterozygote....

Essential Concepts in Muscle Physiology

Skeletal Muscle Anatomy: The Sarcomere

8. A sarcomere (The basic contractile unit)
9. Myofibril (A bundle of myofilaments)
10. T-tubule; terminal cistern (Components of the Triad)

Sarcomere Components Defined

29. Thin filaments
30. I band: (Light band containing only thin filaments; spans from the Z line into the sarcomere.)
31. Z line: (Anchors thin filaments and defines the boundary of a sarcomere.)
32. H band: (Central part of the A band where only thick filaments are present—no overlap with thin filaments.)
33. M line: (The center of the sarcomere, within the H zone, where thick filaments are linked.)

Excitation-Contraction Mechanisms

6. None of these: The correct answer is the Nicotinic ACh receptor, which was not listed.
7. Sarcoplasmic reticulum

Human Nutrition and Body Systems

The digestive, respiratory, excretory, and circulatory systems all play a role in nutrition.

• Digestive system: Introduces foods into the body, and prepares and transforms it to enable its use by cells.
• Respiratory system: Obtains the oxygen cells need and eliminates carbon dioxide produced during cell metabolism.
• Circulatory system: Transports nutrients and oxygen to cells and releases waste substances.
• Excretory system: Releases waste substances outside the organism.

The Digestive System: Function and Structure

The digestive system breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. It is made up of the gastrointestinal (GI) tract and the accessory glands:...

Understanding the Heart's Anatomy

The heart is the pump which circulates the blood throughout the body. It is approximately the size of a person's fist and is located in the chest, slightly left of center.

Myocardium: The Heart's Muscular Walls

The myocardium refers to the muscular walls that make up the heart, essential for its pumping action.

The Heartbeat and Cardiac Cycle

The heartbeat refers to the rhythmic sounds that the heart makes as it pumps blood. This rhythm can also be observed by feeling the arterial pulse. The left and right halves of the heart function as synchronized pumps, working simultaneously.

Phases of the Cardiac Cycle

The cardiac cycle describes the sequence of events that occurs during one complete heartbeat. It consists of...

Characteristics of a Balanced Diet

To maintain a balanced diet, consider the following:

• Eat five moderately sized meals a day to aid digestion.
• Consume a variety of foods from all food groups, following the recommended amounts in the food pyramid or food wheel.
• Incorporate fruits and fresh vegetables daily for essential vitamins.
• Choose fiber-rich foods to promote healthy bowel movements.
• Include unsaturated fats and limit saturated fats and cholesterol to reduce the risk of cardiovascular diseases.
• Consume carbohydrate-rich foods like bread, pasta, rice, and legumes regularly.
• Minimize sugar intake.
• Moderate salt consumption to prevent high blood pressure.
• Reduce the intake of processed and sugary foods (cakes, sweets, etc.).
• Drink 1.5 to 2 liters of

Parts of Eukaryotic Cells:

• Animal: cytoskeleton, cilia and flagella, proteasomes, ribosomes, nucleus, centrioles, vacuoles, golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes.
• Plant: ribosomes, cell wall, cytoskeleton, proteasomes, plastids, vacuoles, golgi apparatus, nucleus, endoplasmic reticulum, mitochondria.

Cell Cycle:

All changes that a cell undergoes from its formation until its division into two new cells.

Phases:

• Interphase: The longest phase, cells do not divide. Before the end of this phase, cells duplicate their DNA.
• Mphase: This short phase, the cell reproduces by cellular division. Two new cells are formed. This can occur in 2 processes:

Mitosis:

The process in which the cell nucleus duplicates with the same genetic material....

What is a Tissue?

A tissue is an aggregate of connected cells that have a similar origin, structure, and function and cooperate to perform a certain function.

Epithelial Tissue

Epithelial tissue covers the body and organ surfaces, lines body cavities, and forms glands. It is involved with protection, absorption, and excretion.

It is made of one or more layers of cells arranged without spaces between them. They can be different shapes—such as flat, prismatic, or cubic—and be arranged in one or more different layers.

Functions of Epithelial Tissue

Epithelia line or cover your body surface, your organs, and all your body cavities, such as your digestive tract, your lungs, blood vessels, and bladder to protect them. Quite often, they perform other...