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

Excretion in Animals and Insects

Excretion is the process of collecting waste products and expelling them outside the body. Some animals don't possess an excretory system and expel waste products directly through the pores.

Insects use Malpighian tubules to expel waste products. The tubules are thin and collect waste. The excretory system in vertebrates consists of various organs: Kidneys (which produce urine), ureters (through which it then flows into the bladder), and the urethra (through which urine is expelled).

How Plants Carry Out Nutrition

Absorption

Absorption is the movement of water and mineral salts from the ground to the inside of the roots. Water and mineral salts are absorbed by the roots. These inorganic nutrients are called raw sap,...

Essential Food Groups and Nutritional Components

Food groups are categorized by their primary nutritional contributions:

• Milk, Milk Derivatives, and Eggs

  Source of proteins, vitamins, and calcium.

• Meat, Poultry, and Fish

  Primarily provide protein.

• Fats and Oils

  Include animal fats (e.g., butter) and vegetable oils. They provide lipids needed when eaten in moderation.

• Cereals, Pulses, Potatoes, and Sugar

  Provide proteins and glucids (carbohydrates).

• Vegetables

  Source of vitamins and fiber.

• Fruit

  Provide glucids (carbohydrates), vitamins, and fiber.

Macronutrients: Energy and Building Blocks

• Glucids (Carbohydrates): Provide energy. Most common forms are starches (found in pulses and potatoes) and sugars (e.g., glucose).
• Fibre: A type of glucid derived from vegetables.

Habitat and Ecological Niche Defined

A habitat is the physical place where a species lives. It provides the natural conditions the species needs to survive. An ecological niche is the way a species relates to the biotic and abiotic factors in an ecosystem.

Two species can share the same habitat, although they do not usually occupy the same ecological niche.

Understanding Trophic Dynamics

Trophic dynamics is the system that describes the position of a living being in a food chain. The system uses trophic levels to explain what an organism eats or is eaten by.

Trophic Pyramids: Graphic Representations

A trophic pyramid is a graphic representation of a particular characteristic at each trophic level. These pyramids are specific to individual ecosystems....

The Biosphere and Ecosphere

The biosphere is the life zone of the Earth, which includes all living organisms and all organic matter. The biosphere is the living component of the ecosphere. The ecosphere includes the large-scale ecosystems of the world. An ecosystem refers to the organisms that live in a particular area, the relationships between them, and their physical environment, such as a lake or a field.

Biomes

Biomes are the large-scale ecosystems of the world.

Ecosystem Components

Animals in terrestrial ecosystems obtain oxygen from the air, while animals in aquatic ecosystems obtain it from the water. Ecosystems consist of two main components:

• Biocenosis: The set of living beings in the ecosystem, including animals, plants, and microorganisms.

Stages of Infectious Disease Development

• 1. Incubation Phase: The time interval between the invasion of pathogens and the manifestation of the first symptoms.
• 2. Overt Disease Phase: The period where clear symptoms and signs of disease appear due to tissue damage.
• 3. Convalescence Phase: The recovery period after the removal of pathogens, where the body repairs damage and restores health.

Treatments for Infectious Diseases

• Serum Therapy: The introduction of antibodies against a specific microbe, produced by another person or animal, into the diseased organism.
• Chemotherapy: The administration of chemical drugs to combat microbes. These can be microbicides (destroying germs) or microbiostatic (preventing reproduction). Key examples include sulfonamides

Divisions of the Nervous System

Central Nervous System

Consists of the brain and spinal cord. It is responsible for receiving and processing information to control bodily functions.

Peripheral Nervous System

Consists of a set of nerves that connect the central nervous system with other organs of the body.

Components of the Central Nervous System

The brain is housed in the skull. The main parts are the cerebrum, the cerebellum, and the medulla oblongata.

The Cerebrum

Appears divided into two hemispheres. The outer part consists of gray matter that receives information from sense organs. The inner zone contains white matter.

The Cerebellum

Located below the cerebrum. The cerebellum coordinates movements such as walking and allows us to maintain balance....

The Initial Stages of Digestion

Digestion begins in the mouth with the mechanical grinding of food (chewing), which is moistened by saliva (insalivation) to initiate chemical digestion. The chewed, saliva-soaked food forms a bolus, which is moved by the tongue into the pharynx during the swallowing process.

Esophageal Transport and Gastric Processing

The bolus travels through the esophagus, driven by peristaltic contractions of the muscular walls. It enters the stomach through the cardia. In the stomach, food mixes with gastric juices, which are rich in hydrochloric acid and digestive enzymes, breaking down the contents to form a slurry called chyme.

Small Intestine and Nutrient Breakdown

The chyme passes gradually from the stomach into the first...

Energy Metabolism in the Human Body

In the cells of our body, a series of chemical reactions which release energy occurs. The final result is CO₂ + H₂O. CO₂ is toxic, so it is stored in the blood and expelled through respiration.

Measuring Food Energy

The energy value of the food is proportional to the energy released when food is burnt in the presence of O₂. Energy released is measured in calories. A calorie is the amount of heat required to increase the temperature of a gram of H₂O by 1ºC. Because it is very small, we use kilocalories.

Energy Sources: Sugars and Lipids

Sugars and lipids provide us with energy. We store them so as to have constantly available energy. Sugars are stored in the liver, while lipids (fat) are stored in various parts...

The Cell: Fundamental Unit of Life

The cell is the smallest unit of an organism capable of acting autonomously. All living organisms are composed of cells, and it is generally accepted that no organism is a living being if it does not contain at least one cell.

Classification by Cell Number

Organisms can be classified based on the number of cells they consist of:

• Unicellular: Consists of a single cell or cell type, such as all bacteria and protozoa (e.g., paramecium, amoeba, ciliates, and so on).
• Multicellular: Consists of more than one cell, which are differentiated to perform specialized functions, as opposed to unicellular organisms (protists and bacteria, among many others) that meet all their vital functions in a single cell.

Key Parts of a

Male Reproductive System

• The Testes

  The testes are the gonads that produce male gametes. These two bodies consist of seminiferous tubules, which give rise to sperm. The testes are covered by a fold of skin called the scrotum.

• The Reproductive Tract

  These tubes carry collected sperm out of the body. They include:

  • Epididymis: Where sperm complete the maturation process that makes them capable of fertilization.
  • Vas Deferens: A continuation of the epididymis that ascends into the abdomen. It is used to store sperm until ejaculation.
  • Urethra: This tube also belongs to the urinary tract, and its final section is housed within the penis.

• The Penis

  The penis is the male copulatory organ. It widens at its end, forming the glans, which is covered with a fold