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

Coordination Systems: Nervous and Hormonal

When a body is small (one cell or more), its component cells are capable of capturing different environmental stimuli and responding to them. When the body is complex and has organs and organ systems, they must act together to perform their roles effectively. The nervous and hormonal systems carry out the coordination function.

Nervous System

Structure of the Neuron: Neurons are highly specialized cells that make up the different tissues and organs of the nervous system. These cells have different morphologies but share common features:

• Soma: Contains the nucleus and cytoplasm with all organelles.
• Axon: A long, unbranched extension with a widened end called the synaptic button.
• Dendrites: Highly branched,

What is Nutrition?

Nutrition is the set of processes by which the body obtains the substances it needs to live. It involves several stages:

• Collection of nutrients through digestion.
• Collection of oxygen through breathing.
• Distribution of nutrients and oxygen through the bloodstream.
• Elimination of waste through excretion and expulsion of carbon dioxide in the breath.

What is Digestion?

Digestion is the process by which foods are broken down into simple substances that can be used by the body. It has these phases:

• Digestion
• Absorption
• Waste Removal

Apparatus Involved in Nutrition

The digestive, respiratory, circulatory, and excretory systems are involved.

Parts of Dentition

Molars, canines, and incisors.

Digestive Tube

It is a muscular tube of different thicknesses...

Genetic Mutations

A mutation is an alteration of genetic material. Key characteristics include being detectable and heritable.

Types of Mutations

• Chromosome Mutations

  These are visible under light microscopy and affect large fragments of chromosomes or entire chromosomes, thus involving many genes. They can impact the structure or number of chromosomes.

  • Structural Alterations: Changes in chromosome structure resulting from broken chromosomes and the rejoining of fragments.
  • Numerical Abnormalities: Changes that alter the normal chromosome number of a species.

• Gene Mutations

  These are not observable by light microscopy and typically involve only a few nucleotides.

Genetic Engineering

Genetic engineering encompasses the study and techniques for the manipulation...

Key Biotechnology Definitions

• Gene: A small segment of DNA that instructs the body on how to produce a specific protein.
• Vector: An agent, generally used as a biological medium for transmitting an organism or genetic material to another.
• Restriction Enzyme: Enzymes that cut DNA at specific target points.

Gene Transfer Process

1. Location and isolation of the gene to be transferred (using restriction enzymes).
2. Selection of the appropriate vector.
3. Union of DNA (gene) into the vector DNA.
4. Transfer of the vector agent to the host cell.
5. Multiplication of the transgenic organism.
6. Purification of the desired substance.

Artificial Insemination

A reproductive technique where sperm are collected and deposited into the vagina during ovulation.

Human Genome Project: Goals

Sensory Receptors: Gateways to Perception

Sensory receptors are specialized nerve cells that capture and transform stimuli into nerve impulses. These vital structures allow the body to perceive and react to its environment.

Classification of Receptors by Stimulus

According to the stimulus to which they are sensitive, receptors are classified as:

• Chemoreceptors: Sensitive to chemical substances.
• Mechanoreceptors: Sensitive to mechanical stimuli such as sound, pressure, friction, or gravity.
• Thermoreceptors: Sensitive to temperature variations.
• Nociceptors: Sensitive to intense pressure, pain, and potentially damaging stimuli.

Location of Sensory Receptors

Sensory receptors are found throughout the body and can be broadly categorized by their location:...

Nutrition Defined

Nutrition is the set of processes by which living organisms transform energy and substances from their environment into their own organic molecules.

Types of Nutrition

• Autotrophs

  Organisms that are able to convert the sun's energy and mineral substances from water and soil into biomolecules.

• Heterotrophs

  Organisms in which nutrition occurs in living organisms that cannot capture the sun's energy, obtaining nutrients by consuming other organisms.

Nutritional Processes

1. Water ascends from roots to leaves through the xylem, which transports water, providing hydrogen.
2. Mineral salts dissolved from the soil provide essential elements like nitrogen, phosphorus, potassium, chloride, iron, magnesium, etc.
3. Carbon dioxide from the air provides

Epithelial Tissue Characteristics

Epithelial tissue is composed of cells with little intercellular substance. The cells are close together and form one or more layers. In addition, there are cells that divide rapidly to replace those that die, as the tissue is subjected to constant friction and injury.

These cells have points of union between them, which can be:

• Tight junctions: These exist between two adjacent membranes. They are very numerous in the epithelium of the small intestine, preventing molecules from passing between cells and forming an impermeable barrier.
• Communicating junctions: These form bridges between cells, connecting the membranes and the cytoplasm. They are found in cardiac muscle cells to facilitate the transmission of contraction

The Nervous System

The nervous system is responsible for detecting and responding appropriately to stimuli that reach the organism. Receptor neurons are specialized to detect stimuli, while effectors carry out the nervous system's commands.

Sensory Organs

The Eye: Structure and Function

The eye is a complex sensory organ responsible for vision. Its primary components include:

• Sclera: The outermost, tough, protective white layer of the eye.
• Choroid: A thin, vascular membrane located between the retina and the sclera, rich in blood vessels that supply nutrients to the eye.
• Retina: The innermost layer at the back of the eye, containing photoreceptor cells (rods and cones) that convert light into neural signals.

The Ear: Functions and Regions

The ear performs...

Cellular Secretions

Secretions include: tears, gastric juice, hormones, and saliva.

Endoplasmic Reticulum (ER)

• Shape: A network of flattened sacs.
• Composition: Plasma membrane (lipoprotein).
• Types:
  • Rough ER (RER/Ergatoplasm): Responsible for protein storage.
  • Smooth ER (SER): Responsible for lipid production and transport.

Golgi Complex

Visible as flattened sacs with cis and trans faces (dictyosomes). Functions include receiving, transporting, dispatching, and packaging substances like mucus (for nasal cavities, trachea, and stomach) and glycoproteins.

• Biological roles: Polysaccharide production for the middle lamella, lysosome formation, and acrosome development in sperm cells.

Glandular Systems

• Unicellular glands: Secretory cells.
• Multicellular glands:

Homologous Structures

Their Counterparts: These structures, like a person's arm and a bat's wing, share the same internal anatomy despite external differences. They are inherited structures that indicate a common ancestor.

Darwin's Example: Giraffe Necks

Darwin's Example: Giraffes exhibit population variations, such as differences in neck and leg length. During unfavorable seasons, individuals with longer necks and legs survive by reaching leaves and reproduce. Those with shorter necks and legs may die of hunger. Over generations, this leads to the prevalence of the 'long-necked' giraffe.

Lamarck's Theory

Lamarck: Proposed that primitive creatures stretched parts of their bodies, and these acquired traits were passed down through generations.

Ice