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

• Centrioles: Located near the nucleus, they help to organize cell division.

Cell Membrane

• Regulates what enters and leaves the cell.
• Protects and supports the cell.
• Structure: Lipid bilayer—a double-layered sheet that gives it a flexible structure.

Vacuole

• Large, saclike, membrane-enclosed structures.
• Function: Store materials like water, salts, proteins, and carbohydrates.
• Structure: In many cells, there is a single central vacuole filled with liquid.

Vesicles

• Smaller membrane-enclosed structures.
• Function: Store and move materials between cell organelles, and to and from the cell surface.

Lysosome

• Small organelles filled with enzymes (lysosomes).
• Function: Break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest

The Digestive System

The digestive system is responsible for the ingestion, digestion, absorption, and elimination of food. It transforms food into nutrients through three main processes:

1. Mechanical Digestion: Chewing, grinding, crushing, and mixing of food to break it down into smaller pieces.
2. Chemical Digestion: Digestive juices break down macromolecules in food into smaller molecules that can be absorbed.
3. Absorption: Nutrients are absorbed into the bloodstream and transported to cells throughout the body.

Ingestion

Ingestion begins when food enters the mouth. Key steps include:

• Mastication (Chewing): Teeth tear and break food into smaller pieces.
• Salivation: Saliva mixes with food, forming a bolus and aiding in swallowing.
• Swallowing: The tongue

Core Functions of the Liver

• Hormone Regulation: The liver synthesizes and breaks down hormones, including cholesterol, testosterone, and estrogen.
• Blood Glucose Regulation: It maintains blood sugar levels. The liver stores and produces sugar; during meals, it converts sugar into glycogen for later use when the body requires energy.
• Synthesis and Storage of Nutrients:
  • Amino Acids: Assembles them into complex proteins as needed.
  • Proteins: Converts toxic ammonia into less toxic urea.
  • Vitamins: Stores fat-soluble vitamins (A, D, E, and K).
  • Fats: Metabolizes lipids.
• Blood Circulation and Filtration: Processes all food, nutrients, alcohol, drugs, and other materials entering the bloodstream.
• Bile Drainage: Bile is a bitter, greenish-brown, soap-like substance

Nutrients and Life Stages

The quantity of nutrients that our body needs depends on the stage of life we are in.

• Breastfeeding (0–6 months): Requires breast milk.
• Childhood: Diet gradually becomes similar to an adult diet. Children generally require more calories for growth.
• Adolescence: Nutritional needs are similar to adults.

Nutritional Needs During Adulthood

Specific needs apply, especially during pregnancy. Pregnant women require approximately 300 kcal more per day, increased proteins, specific vitamins (e.g., folic acid), minerals (e.g., calcium), water, and fiber.

Nutritional Needs in Old Age

Older adults generally require similar nutrients to adults, but fewer calories overall.

Macronutrient Distribution and Calories

Recommended Daily Allowance...

Metaphase I and Independent Assortment

Independent assortment is the process where the chromosomes move randomly to separate poles during meiosis. A gamete will end up with 23 chromosomes after meiosis, but independent assortment means that each gamete will have many different combinations of chromosomes. During this phase, paired chromosomes line up along the middle of the cell.

Spermatogenesis and Oogenesis

Spermatogenesis

• Transformation of spermatogonia into spermatozoa (sperm).
• Meiosis does not begin until puberty.
• This is the production of the male gamete.

Oogenesis

• This is the production of the female gamete.
• These develop prenatally in the fetus.
• Mitosis of primordial germ cells produces oogonia.

Mechanisms of Allelic Variation

• Gene mutations: These

Circulatory System

The system that circulates blood and lymph through the body, consisting of the heart, blood vessels, blood, lymph, and the lymphatic vessels and glands.

• Heart: A hollow muscular organ that pumps blood through the circulatory system by contracting. It contains four chambers and two ventricles.
• Veins: Tubes forming part of the blood circulation system, carrying deoxygenated blood toward the heart.
• Arteries: Muscular-walled tubes that convey oxygenated blood from the heart to all parts of the body.

Nervous System

The network of nerve cells and fibers that transmits nerve impulses between parts of the body.

• Spinal Cord: The main pathway for information connecting the brain and peripheral nervous system.
• Nerves: Structures that carry

Pulmonary Circuit

The pulmonary circuit involves the right side of the heart, which pumps blood that is partially depleted of oxygen content and contains elevated CO2 as a result of gas exchange in various tissues. This blood is delivered from the right side of the heart into the lungs. In the lungs, oxygen is loaded into the blood, and CO2 is released. This oxygenated blood then travels to the left side of the heart and is pumped to body tissues via the systemic circuit. The systemic circuit pumps an equal amount of blood from both ventricles. Generally, veins pump blood back to the heart, while arteries pump blood away from the heart.

Cardiac Drift

Cardiac drift refers to the increase in heart rate and decrease in stroke volume observed during...

The Human Nervous System

Core Components

• CNS (Central Nervous System): Made up of the brain and spinal cord.
• PNS (Peripheral Nervous System): Made up of the rest of the nerves in the body. These connect the CNS with sensory organs, muscles, blood vessels, and glands.

Key Terminology

• Neurones: Connections of many long, thin nerve cells.
• Effectors: Carry out actions in response to messages from the CNS.
• Receptors: Sense changes in the environment (eyes, nose, mouth, skin, ears).
• Stimuli: Provide the information to the receptors.
• Sense Organ: Organs that contain the receptors.

Types of Neurones

• Sensory Neurone: Pass electrical messages from the receptor to the CNS.
• Motor Neurone: Pass messages from the CNS to effectors (muscles/glands).
• Relay Neurone: Pick

Dental Articulators

An articulator is a mechanical device that represents the temporomandibular joints and jaw members. Maxillary and mandibular casts may be attached to simulate jaw movements.

Uses of Articulators

• Mounting diagnostic casts for diagnosis, treatment planning, and patient presentation.
• Fabrication of occlusal surfaces of dental restorations and lost dental parts.
• Arrangement of artificial teeth for complete and removable partial dentures.

Advantages of Using an Articulator

• Properly mounted casts allow the operator to better visualize the patient’s occlusion.
• When articulating teeth for a complete denture, the lingual view provided by the articulator is essential for developing a proper occlusal scheme.
• Patient cooperation is not a factor

Nature of Science

Science attempts to study and gain information about nature. Science poses hypotheses (usually based on observations) and attempts to explain these hypotheses by observations, inferences, and experimentation.

Hypothesis vs. Theory

A theory is the basis of facts and how they work together. A hypothesis is a question or an educated guess.

Properties of Water

Water is polar. Water is most dense at 4 degrees Celsius.

Cell Organelles and Their Functions

Chromosomes

• Usually in the form of chromatin
• Contains genetic information
• Composed of DNA
• Thicken for cellular division
• Set number per species (e.g., 23 pairs for humans)

Nuclear Membrane

• Surrounds nucleus
• Composed of two layers
• Numerous openings for nuclear traffic

Nucleolus

• Spherical shape
• Visible