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

Introduction

Humans are heterotrophs, meaning they cannot create their own organic matter. They obtain energy by ingesting substances from other organisms.

Food: Substances from other living things that are ingested.

Nutrients: Simple molecules contained in foods, necessary for life.

Eating: Conscious, voluntary process by which foods are taken from the outside environment.

Nutrition: Complex, unconscious, and mostly involuntary process by which foods are transformed into nutrients.

Carbohydrates (Glucides)

Energy-providing nutrients.

Monosaccharides

Formed only by one molecule.

• Examples: Glucose (cane sugar), fructose (fruit sugar)

Disaccharides

Formed by two molecules.

• Examples: Sucrose (cane sugar), lactose (sugar of milk)

Mono and disaccharides are sweets,...

The Internal Environment and Nutrition

All cells need to live in an internal environment that provides them with all the food and nutrients they need and allows cells to release waste substances. It is formed of interstitial plasma, and the plasma has to be continually renewed thanks to the blood, which transports nutrients and removes waste products. The circulatory system connects the other three systems involved in nutrition.

Blood Composition

• Blood Plasma (55%): Made up of water with minerals (90%), nutrients (glucose, amino acids, vitamins, etc.), waste products (urea, uric acid, CO2), proteins, and dissolved hormones.
• Blood Cells (45%): Includes erythrocytes (98-99%), leukocytes (granulocytes and agranulocytes), and platelets (1-2%).

Blood

Components of the Respiratory Tract

These are the nasal cavities, pharynx, larynx, trachea, bronchi, and bronchioles. Inside the larynx, there are two ring-shaped folds (vocal cords). They create sound when the passage of air makes them vibrate.

Lungs: Site of Gas Exchange

This is where the gas exchange between blood and air takes place.

Respiratory Tract Function

When air reaches the lungs, it needs to be clean, humid, and warm. This preparation process takes place in the respiratory tract.

Nasal Cavity: Air Entry Point

This is the place where air enters the body. In the first section, the internal wall has several capillaries which warm up the air because they carry blood. Mucus purifies and humidifies the air.

Pharynx: Shared Passageway

This area...

Essential Medical Concepts

Key Definitions in Health and Immunity

What is Health?

Health is a combination of physical, mental, and social well-being, indicating a state where an individual is not suffering from a disease.

Understanding Antigens

An antigen is a substance that is perceived by lymphocytes and triggers a specific immune response.

Phagocytes: Immune System Defenders

A phagocyte is a specific type of white blood cell that activates when a pathogen crosses the first line of defense.

The Body's Defense Mechanisms

Understanding Immunity and Protection

Non-Specific Immune Response

When a pathogen crosses the first line of defense, the second line of defense is activated. This non-specific response is carried out by specific white blood cells, such...

Homeostasis and Environmental Response

All living things interact with their environment, including their surroundings and other organisms.

The environment is constantly changing. To survive and reproduce, living organisms must detect these changes and respond appropriately.

Responding to Stimuli

1. A stimulus is detected by receptors (structures or organs).
2. The stimulus is relayed to coordination systems, which interpret the signal and produce a response.
3. The organism responds using effectors (organs or structures).

Maintaining Internal Balance

To survive, living organisms must regulate their internal conditions.

Examples of internal conditions include temperature, water content, and concentrations of mineral salts and glucose in the blood.

Changes in...

Contraceptive Methods

Rhythm Method

Observes the menstrual cycle to calculate the day of ovulation. Advantages: A natural method with no side effects. Disadvantages: Imprecise; not a barrier method and does not protect against STIs.

Body Temperature Method

Observes the basal body temperature in women to calculate the day of ovulation.

Male Condom

A plastic sleeve placed on the penis to stop sperm during ejaculation. Advantages: Very cheap, easy to find, and a barrier method. Disadvantages: 98% effectiveness; some people experience side effects.

Female Condom

A plastic sleeve placed inside the vagina to stop sperm during ejaculation. Advantages: Cheap and a barrier method. Disadvantages: 95% effectiveness; more difficult to find; potential side effects....

Homeostasis and Body Interaction

The interaction process fulfills two objectives:

• Adapt the body to changing conditions.
• Connect and coordinate the different parts of our body.

Homeostatic process is a series of different processes in which the body's stability is maintained. These processes allow the organs to maintain a balanced condition so they can function properly.

Components of the Nervous System Pathway

• The sensory organ: Receives information from the environment.
• The nervous system: Transforms the stimuli into nerve impulses.
• The effector organs: Receive the response from the nervous system.

Types of Effector Systems

1. Locomotor system: Formed of muscles and bones.
2. Endocrine system: Produces regulating hormones.

Neurons: Specialized Nerve Cells

Neurons...

Main Characteristics of Vertebrate Animals

Vertebrate animals belong to the Animal Kingdom and possess the following characteristics:

• They have an internal skeleton that allows movement, protects the organs, and gives support to their body.
• They have blood to carry nutrients and waste products throughout the body.
• They have articulated limbs (fins, wings, or legs).

We are going to study the following vertebrate groups:

Classification and Features of Fish

• Aquatic: They have a fusiform body (thinner at the tips) and fins. They breathe through gills.
• Poikilothermic: They cannot maintain a constant body temperature.
• Lateral line: A line crossing their body that is able to detect vibrations in the water.
• External fertilization: Gametes join in the environment,

Endocrine System Regulation

How is the endocrine system regulated? Endocrine gland activity is regulated by the brain. The brain manages the endocrine system through two glands: the hypothalamus and the pituitary glands. The hypothalamus directs, and the pituitary glands produce and secrete.

Neuron Structure and Classification

Neurons: These transmit messages (nerve impulses) and have a unique appearance.

• Cell body: This is where the nucleus is located; it contains most of the cytoplasm and organelles. It forms part of the grey matter.
• Dendrites: These are branched projections connected to other neurons that receive information from them.
• Axon: A long tail structure where information passes from here to the next neuron or cell. A group of axons is

Animal Nutrition and Digestion

Animals are heterotrophs that obtain nutrients through feeding. Different feeding methods include absorption directly from the environment, filtration of food present in water, and ingestion through the mouth. Digestion is the process where food is transformed into nutrients.

Digestive Mechanisms

• Sponges: Filter food particles from water entering through pores.
• Mechanical Digestion: Breaking food into smaller pieces.
• Chemical Digestion: Separating nutrients from food.
• Absorption: Blood absorbs nutrients for the body.
• Excretion: Expulsion of waste from the body.

Digestive Structures

• Gastrovascular Cavities: Sac-shaped structures with one opening for food intake and waste expulsion.
• Digestive Tracts: Tubes with two openings: