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

Living vs. Non-Living Things

Both living and non-living things are made up of matter. All living things share certain common characteristics. These characteristics can help us identify a mineral as a non-living thing and a butterfly as a living one.

Composition of Non-Living Things

Non-living things are made up of inorganic matter. The most abundant chemical elements include:

• Oxygen
• Silicon
• Aluminum
• Iron

Composition of Living Things

Living things are made up of chemical elements called bioelements. The most abundant are:

• Oxygen
• Nitrogen
• Phosphorus
• Sulfur

Key Characteristics of Life

Nutrition

Autotrophic Nutrition

Organisms with autotrophic nutrition capture energy from their environment and use it to transform inorganic substances, such as water, carbon dioxide,... Continue reading "Key Differences Between Living and Non-Living Things" »

Autotrophs and Heterotrophs Defined

F.5.1 Define the terms photoautotroph, photoheterotroph, chemoautotroph, and chemoheterotroph

Photoautotroph: An organism that uses light energy to generate ATP and produce organic compounds from inorganic substances.

Photoheterotroph: An organism that uses light energy to generate ATP and obtains organic compounds from other organisms.

Chemoautotroph: An organism that uses energy from chemical reactions to generate ATP and produce organic compounds from inorganic substances.

Chemoheterotroph: An organism that uses energy from chemical reactions to generate ATP and obtains organic compounds from other organisms.

Examples of Autotrophs and Heterotrophs

F.5.2 State one example of a photoautotroph, photoheterotroph,

... Continue reading "Autotrophs vs. Heterotrophs: Energy & Carbon Sources" »

Animal Respiration

Breathing is essential for respiration. Animals breathe by inhaling oxygen and exhaling carbon dioxide. This gas exchange occurs via the respiratory system.

Respiratory Systems

Respiratory systems require thin, moist surfaces covered in blood vessels for efficient gas exchange. This facilitates oxygen uptake and carbon dioxide expulsion.

Cutaneous Respiration

Gas exchange through the skin (thin and moist). Examples include earthworms and adult amphibians.

Branchial Respiration

Gas exchange through gills (surrounded by blood vessels). Examples include fish and some crustaceans.

Tracheal Respiration

Gas exchange via internal tubes (tracheae) carrying air directly to cells. Examples include terrestrial arthropods.

Pulmonary Respiration

Gas... Continue reading "Animal Respiration, Circulation, and Excretion" »

Evidence of Evolution

1. Anatomical and Morphological Evidence:

• Homologous organs
• Analogous and vestigial organs

Fossil Evidence:

Fossils reveal that organisms in the Earth's past were different from nowadays.

Embryonic Evidence:

Some embryos from different species are similar, indicating an evolutionary relationship between them.

Biogeographical Evidence:

Biogeographical patterns can be explained according to theories of evolution.

Molecular Evidence:

Molecular similarities reveal the degree of relatedness between two groups.

Other Evidence:

• Parasites: organisms that live off other species.
• Behavior: based on genetic inheritance.

Present-Day Theories of Evolution

Neo-Darwinism considers that natural selection does not act on the individual in isolation... Continue reading "Evidence of Evolution and Present-Day Theories" »

Origin of Life Hypotheses

The Oparin-Haldane hypothesis suggests that life arose gradually from inorganic molecules, with "building blocks" like amino acids forming first and then combining to make complex polymers.

The primitive atmosphere was reducing, containing water vapor and ammonia.

Both Oparin and Haldane proposed that the first life forms were heterotrophs.

Oparin's Work with Coacervates

Oparin's work with coacervates confirmed that enzymes fundamental for the biochemical reactions of metabolism functioned more efficiently when contained within membrane-bound spheres than when free in an aqueous solution.

Haldane's Primordial Soup Idea

Haldane's ideas about the origin of life were very similar to Oparin's. Haldane proposed that the primordial... Continue reading "Origin of Life: Oparin-Haldane & Miller-Urey" »

These are energetic and structural substances found in many foods that we eat daily. There are two groups:

Simple Carbohydrates

• Monosaccharides: They are the simplest ones.
• Disaccharides: They are formed by two monosaccharides joined together.

Complex Carbohydrates (Polysaccharides)

They are neither sweet nor crystalline and they are not soluble in water. They include:

• Starch: It is made up of glucose molecules.
• Cellulose: It makes up vegetal fibre and forms the plant cellular wall. It is also made up of glucose molecules.

Inorganic Substances

These are small inorganic substances with variable composition. In solid state, they are structural. In dissolution, they are regulatory and allow our organs to function correctly and intervene in the regulation.... Continue reading "Energetic and Structural Substances in Foods" »

Pituitary

• Location: Head 2 lobes - anterior lobe
• Hormone: growth hormone
• Target organ: Whole body, skeleton
• Function: stimulate the growth

• Location: Head 2 lobes - anterior lobe
• Hormone: Thyroid stimulating hormone (TSH)
• Target organ: Thyroid
• Function: stimulate production of thyroid hormones

• Location: Head 2 lobes - anterior lobe
• Hormone: Gonadotropes. Follicle stimulating hormone (FSH) Luteinizing hormone (LH)
• Target organ: Ovaries and testes
• Function: action ovaries and testes

• Location: Head 2 lobes - anterior lobe
• Hormone: Adrenocorticotropic hormone (ACTH)
• Target organ: Adrenal glands
• Function: Stimulate the secretion of adrenal glands

• Location: Head 2 lobes - anterior lobe
• Hormone: Prolactin
• Target organ: breasts
• Function: stimulates breast growth and milk

... Continue reading "Endocrine System Glands and Hormones: Location and Functions" »

Ectoparasites: True or False Statements

Test your knowledge on ectoparasites with these statements:

• Ectoparasites do not produce skin lesions. False (Many ectoparasites, like scabies mites, cause significant skin lesions.)
• Skin appendages are infested by ectoparasites. True (This includes hair, sebaceous glands, and sometimes nails.)
• Infestation by head and body lice refers to Bediculosis. False (The correct term is Pediculosis.)
• Hair and sebaceous glands are parts that can be affected by ectoparasites. True
• Ectoparasites are considered organisms. True (They are living organisms that live on the exterior of a host.)
• Many reports of ectoparasitic diseases have disappeared. False (Ectoparasitic diseases remain prevalent globally.)
• Scabies are not found

... Continue reading "Biological Concepts: Ectoparasites, Tissues, Evolution" »

Enzyme Function and Segregation

1. What is the function of amylase? What is the function of pepsin? Why are they segregated?

• Amylase: Amylase begins the digestive process by breaking down starch when you chew your food, converting it into a smaller carbohydrate.
• Pepsin: Pepsin helps digest the proteins in food.

They are segregated because amylase functions primarily in the mouth (saliva), while pepsin functions in the highly acidic environment of the stomach.

Essential Digestive Terminology

2. Definitions:

• Chyme: Is the semi-fluid mass of partly digested food that is expelled by the stomach.
• Intestinal Flora: Is the symbiotic bacteria occurring naturally in the gut.
• Defecation: Is the final action of digestion, by which organisms eliminate solid, semi-

... Continue reading "Essential Concepts of Human Digestion and Metabolism" »

The Significance of Meiosis

Why Meiosis?

 Meiosis generates diversity by ensuring that the gametes it gives rise to will differ genetically from one another.

 Meiosis is unlike regular cell division, or mitosis, which produces daughter cells that are exact genetic copies of parent cells.

 Evolution is spurred on by differences among offspring, and meiosis and sexual reproduction ensure such differences.

 By contrast, asexual reproduction, as is seen in bacteria and other organisms, produces organisms that are exact genetic copies, or clones, of the parental organism.

 The genetic diversity brought about by Meiosis and sexual reproduction is responsible, to a significant extent, for the great diversity of lifeforms seen in the living... Continue reading "Understanding Meiosis: The Process of Genetic Diversity and Reproduction" »