Notes, summaries, assignments, exams, and problems for Biology

Vertebrata

Vertebrates are characterized by a backbone created from small parts called vertebrae and an endoskeleton. The endoskeleton can be made of:

• Cartilage (Cyclostomata, Chondrichthyes)
• Bones (Osteichthyes, Amphibians, Reptiles)

Key systems include:

• Central Nervous System: Brain, spinal cord, peripheral nerves forming a tubular nervous system.
• Vascular System: Closed, chambered heart.
• Breathing System: Gills, lungs.
• Excretory System: Kidneys.

They mostly have four limbs, although these are sometimes modified (e.g., fish fins, bird wings) or absent (e.g., snakes).

Cyclostomata (Jawless Fish)

These animals lived on Earth 500 million years ago. They live in shallow seas, mild climatic areas, and sometimes in fresh water. Their mouth opening is round;... Continue reading "Vertebrate Animal Groups and Features" »

Functions of the Endocrine System

The endocrine system performs several vital roles in maintaining the body's internal environment. Its most important functions include:

• Reproduction
• Metabolism and Energy Balance
• Growth and Development
• Body Defenses
• General Homeostasis: Maintaining water, nutrient, and salt balance in the blood.

While all are critical, homeostasis is often considered the most important as it ensures a stable internal environment for all other processes.

Major Endocrine Glands and Their Hormones

The following table details the primary endocrine glands, the hormones they secrete, and their specific functions:

Cell Theory

Cells are the basic unit of life, all organisms are made up of 1 or more cells, and all cells arise from existing cells.

Contributors to Cell Theory

Hooke

Robert Hooke, a British scientist, first named cells in 1665. He observed cork with a microscope.

Scheiden

Matthias Jakob Schleiden, a German botanist, concluded that plants were made of cells.

Schwann

Theodor Schwann, a German zoologist, found that all living things are made of cells.

Leeuwenhoek

Antonie van Leeuwenhoek, a Dutch fabric store owner, ground a lens that magnified the microscope 200x's.

Virchow

Rudolf Virchow, a German doctor, disputed the idea of spontaneous generation (the idea that cells come from nothing) and concluded that cells come from other cells.

Cell Structures

Cell

Food and Nutrients

Food is our primary source of nutrients. But what are nutrients exactly?

Nutrients: The Essentials for Life

NUTRIENTS are biomolecules that our bodies need to sustain vital functions. They are the chemical components of food, acting as the building blocks and energy sources our cells need to survive.

Why We Need Nutrients

Cells require nutrients to fulfill three fundamental requirements:

1. Energetic: Certain nutrients, like lipids and carbohydrates, are broken down in our mitochondria to release energy. This energy powers essential functions such as movement, temperature regulation, and more.
2. Structural: Some nutrients, including proteins, lipids, and mineral salts, serve as the building blocks for various body structures. These structures

Life Processes

Life processes are the processes that are necessary for an organism to stay alive. Examples include nutrition and respiration.

Criteria of Life

• Growth
• Movement

Nutrition

Nutrition is the process in which an organism takes in food, utilizes it to get energy for growth, repair, maintenance, etc., and excretes the waste materials from the body.

Types of Nutrition

1. Autotrophic Nutrition

(Auto = self; trophos = nourishment) Examples: Plants, Algae, Blue-green bacteria.

• Process: Photosynthesis (Photo = light; Synthesis = to combine)
• Raw Materials:
  • Carbon dioxide
  • Water
• Energy Conversion: Light/Solar energy to Chemical energy
• Role of Chlorophyll: To trap the sun's energy for photosynthesis
• Factors for Autotrophic Nutrition:
  • Carbon dioxide
  • Water
  • Light
  • Temperature
• Events/

Cellular Interaction and Responses

Cellular interaction is the capacity of cells to detect changes in their environment and respond to them correctly.

Types of Cellular Responses

Static Response

In a static response, there is no movement produced. Rather, the cell responds in a different way, for example, by secreting a substance.

Dynamic Response (Taxis)

In a dynamic response, the cell responds by moving. These movements are collectively called taxis (plural: taxa). They are considered:

• Positive: If the cell moves towards the stimulus.
• Negative: If the cell moves away from the stimulus.

Mechanisms of Cellular Movement

Flagellar and Ciliary Movement

This type of movement is produced in cells that have cilia (many tiny structures) or flagella (longer than... Continue reading "Cellular Responses, Movement, and Reproduction Mechanisms" »

The Origin of New Species

The changes that living things experience as time passes lead to the creation of new species. In this long and complex process, there are 4 stages:

1. Production of Evolutionary Changes in Populations

This happens because natural selection favors some individuals and not others. As a consequence, the new populations are different from the original ones, although they still belong to the same species.

2. Genetic Isolation of the New Population

So that a new species can evolve, it is essential that the members of the new population do not reproduce with those of the previous population. In other words, they become independent and stop sharing genetic information with the original population.

3. Gradual Differentiation

After... Continue reading "The Origin of New Species and Human Evolution" »

Understanding and Managing Stress

Concept of Stress

Stress, an uneasy experience of pressure, can stem from various sources: yourself, others, and the environment. Modern life's fast pace creates numerous pressures, leading to frequent stressful situations. Effective stress management starts with understanding its sources and how to address them.

Self-Inflicted Stress

Sometimes, we create our own stress. This isn't always negative. Eustress, or positive stress, can produce beneficial results. Its counterpart, distress, is the negative dimension of stress.

Environmentally Caused Stress

External factors can also induce stress. Imagine your crops are ready for harvest, but continuous rain creates worry and helplessness. This stress originates from... Continue reading "Stress Management Techniques" »

The Human Heart: Chambers, Vessels, and Blood Flow

Heart Action: Blood Collection, Pumping, and Valve Function

The right atrium collects blood from the superior and inferior vena cava, and the left atrium collects blood from the pulmonary veins. This blood then flows into the right and left ventricles, which pump the blood into the arteries. The direction of blood flow is controlled by the atrioventricular valves and semilunar valves. When the atria contract, the blood flows through the open atrioventricular valves into the ventricles. At this stage, the semilunar valves are closed, so the ventricles fill with blood. The ventricles then contract, which causes a rise in pressure. This rise in pressure first causes the atrioventricular valves to... Continue reading "Human Circulatory and Immune System Fundamentals" »

Parts of Eukaryotic Cells:

• Animal: cytoskeleton, cilia and flagella, proteasomes, ribosomes, nucleus, centrioles, vacuoles, golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes.
• Plant: ribosomes, cell wall, cytoskeleton, proteasomes, plastids, vacuoles, golgi apparatus, nucleus, endoplasmic reticulum, mitochondria.

Cell Cycle:

All changes that a cell undergoes from its formation until its division into two new cells.

Phases:

• Interphase: The longest phase, cells do not divide. Before the end of this phase, cells duplicate their DNA.
• Mphase: This short phase, the cell reproduces by cellular division. Two new cells are formed. This can occur in 2 processes:

Mitosis:

The process in which the cell nucleus duplicates with the same genetic material.... Continue reading "Parts of Eukaryotic Cells and the Cell Cycle" »