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

Mutations: Changes in DNA Sequence

Mutations are changes in the DNA sequence of a cell that can be transferred to other cells resulting from it. These alterations are fundamental to genetic variation and evolution.

Types of Mutations

1. According to the Effect on the Individual

• Harmful Mutations: These affect the basic structures of individuals and can cause severe health issues or even death.
• Beneficial Mutations: These enhance an individual's survival and reproductive success. They are crucial for the genetic variability and adaptation of a population.
• Neutral Mutations: These do not significantly affect the survival or reproductive fitness of the individual, either positively or negatively.

2. According to the Cells They Affect

• Germline Mutations:

The Human Immune System

Understanding the Immune System

Human beings possess a sophisticated defense system known as the immune system. This intricate network of mechanisms provides the body with resistance to infectious agents or pathogens.

Innate or Non-Specific Immunity

We are born with innate or natural immunity, which is a form of non-specific immunity. It develops while we are in the womb and includes several key components:

Components of Innate Immunity

• External Defenses: The skin, which is largely impermeable to most microorganisms, and mucous membranes. These tissues line internal passageways and secrete mucus that prevents bacterial growth.
• Bodily Secretions: Substances like tears and saliva destroy or damage pathogens. Natural bacterial

Embryonic Development

The Human Nervous System: Divisions and Functions

The human nervous system is a complex network responsible for controlling all body activities. It is broadly divided into two main parts:

• Central Nervous System (CNS): Protected by bones (skull and spine) and three membranes called meninges.
• Peripheral Nervous System (PNS): Composed of nerves that connect receptors and effectors to the central nervous system.

Central Nervous System (CNS)

The Central Nervous System (CNS) is the body's control center, formed by the brain (located inside the skull) and the spinal cord (located inside the spine).

The Brain: Control Center of the Body

The brain is the most complex organ in the human body, responsible for thought, emotion, memory, and movement. It comprises...

Step 1: Glycolysis - What Happens?

1 glucose molecule is split into two 3-carbon molecules called pyruvate.

Who Controls It? Enzymes. Where? Cytosol. Result? Two molecules of ATP are produced.

Step 2: Oxidative Respiration - The pyruvate molecules made during glycolysis still have a lot of potential to make more energy (ATP). What Happens? The 2 pyruvate molecules now go through oxidative respiration where they produce carbon dioxide, water, and 34 ATP! Where? Mitochondria.

Three Metabolic Pathways - Within these two systems, aerobic vs. anaerobic, there are three main metabolic pathways by which ATP energy reserves are restored.

1. The ATP-PC Pathway: Anaerobic Alactic.

2. The Glycolysis Pathway: Anaerobic Lactic.

3. Cellular Respiration: Aerobic - It is

Common Health Disorders

Sensory Organ Issues

• Eyes:
  • Short-sightedness (Myopia): Eyeball too long. Images focus in front of the retina.
  • Long-sightedness: Images focus behind the retina.
  • Cataracts: The crystalline lens loses transparency until it becomes opaque.
  • Conjunctivitis: Inflammation in the conjunctiva.
  • Astigmatism: Irregularly shaped cornea; objects appear distorted or blurred.
• Skin:
  • Psoriasis: Skin patches covered with silver scales.
  • Urticaria: Allergic reaction, often to food or medicine.
• Ear:
  • Otitis: Acute inflammation.
  • Deafness: Hearing loss.
• Nasal Cavity:
  • Rhinitis: Inflammation in the nasal respiratory membrane, often caused by allergies.

Mental Health Conditions

• Phobias: An anxiety disorder due to a persistent, irrational fear (e.g., fear of confined

Human Reproductive System Fundamentals

Male Reproductive System

• Function: Produces sperm cells and delivers them into the female reproductive system for egg fertilization.
• Testes: Two egg-shaped organs, the primary gamete-producing organs. Each testis contains seminiferous tubules where sperm forms.
• Scrotum Temperature: Sperm formation requires the scrotum to be 2-3°C cooler than normal body temperature (37°C).
• Sperm Production Lifespan: Men produce sperm from puberty until androgen production ceases.
• Meiosis Outcome: Each cell undergoing meiosis produces four functional sperm cells.

Female Reproductive System

• Function: Prepares gametes for potential fertilization.
• Ovaries: Two almond-shaped organs located in the lower abdomen, serving as the primary

What is the primary waste product in urine?

Ammonia

Identify the body functions that the urinary system helps regulate and maintain.

• Eliminate waste
• Primarily Ammonia
• Conserve nutrients
• Prevent excretion
• Regulate and maintain:

• Blood volume
• Blood pressure
• Conserve ions (sodium, potassium, calcium)
• Assist liver in detoxifying poisons

Briefly, in an essay, list and explain the three steps in urine production that occurs in the nephron. Terms like tubular reabsorption will not be given in question!

1. Glomerular filtration
2. Movement of protein-free solution and solutes from glomerulus into capsule space
3. Tubular reabsorption
4. Return of most of the fluid and solutes back into the capillaries
5. Tubular secretion
6. Addition of some solutes from the capillaries into the tubule

What

The Digestive System

The digestive system transforms food into nutrients that are the right size to reach body cells and be absorbed. To carry out this function, the digestive system consists of a group of organs and structures: the digestive tract and the accessory glands.

The Digestive Tract

The digestive tract, in order from top to bottom, includes:

• Mouth: The entry point of the digestive tract. It contains:
  • Teeth to bite and break food into small pieces.
  • A tongue to mix and swallow food, and enable the sense of taste.
  • Salivary glands.
• Pharynx: A cavity shared by the digestive and respiratory systems. Food passes towards the esophagus. The epiglottis, a small, flexible cartilage, prevents food from reaching the respiratory tract.
• Esophagus: A tube