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

Item 14. Physical Agents: Thermal Environment

Introduction

Thermal environment refers to environmental conditions including:

• Temperature
• Humidity
• Physical activity

Homeotherms

Homeotherms maintain internal temperature within very narrow ranges.

• Danger: Heat stress
• Heat discomfort
• Comfort
• Discomfort from cold
• Danger: Hypothermia

Thermal Equilibrium

Thermal equilibrium between body and environment involves mechanisms of thermoregulation.

Mechanisms of Thermoregulation

Q = M ± R ± C - E

• Q: Heat generated or heat buildup
• M: Metabolic activity
• R: Radiation exchange
• C: Exchange by convection
• E: Heat lost by evaporation

Radiation Exchange (R)

Heat exchange that originates between two solid bodies in proximity.

Exchange by Convection (C)

Mechanism by which the body exchanges... Continue reading "Thermal Environment: Effects, Regulation, and Comfort" »

Soma Cells: These cells comprise the whole body, excluding the germ cells.

Germ Line: Specialized cells in reproductive organs responsible for producing gametes.

Karyogamy: The fusion of cell nuclei.

Sexual Dimorphism: Morphological differences between males and females of a species.

Fecundity: The ability to produce offspring.

Withers: When two hermaphroditic individuals mate and fertilize each other.

Parthenogenesis: A phenomenon where an unfertilized egg develops into a normal adult.

Receptaculum Seminis: A storage location for sperm after mating.

Spermatophores: Packets containing sperm that are transferred to females.

Segmentation: A series of rapid cell divisions during early embryonic development.

Morula: A solid ball of cells in the early embryo.... Continue reading "Key Concepts in Reproduction and Embryonic Development" »

Mendel's Laws

Mendel explained the observations made during years of crossing different types of peas in the gardens of a monastery. He collected the general laws of inheritance that later became known as Mendel's laws.

Double Helix DNA

DNA carries the genetic information. DNA is a molecule composed of four simple units, repeated often and combined in different ways (called nucleotides). There are four types of DNA nucleotides: cytosine, guanine, thymine, and adenine. A single DNA molecule is formed by two chains of nucleotides linked and facing each other, with a structure that forms a spiral staircase: a double helix.

Replication of DNA

DNA contains genetic information. When the cell divides, it is capable of making an exact copy of the entire... Continue reading "Mendel's Laws, DNA, Genes, and the Genetic Code" »

Biomolecules and Genetic Information

Biomolecules form long chains, such as in genetic information storage. These chains consist of repeating nucleotides. A nucleotide is composed of a nitrogenous base, a pentose sugar (like am5C), and a phosphate group. A nucleoside is simply a base plus a pentose sugar.

Nitrogenous bases include adenine (A), thymine (T), uracil (U), and guanine (G). Purine bases (A and G) have a two-ring structure, while pyrimidine bases (C, T, and U) have a single-ring structure. These bases contain the genetic code necessary for protein synthesis. Approximately 3000 base pairs are needed to code for a single protein. The human genome contains 46 chromosomes (23 pairs), with 22 pairs being autosomes and one pair being sex... Continue reading "Biomolecules, Genetics, and Chromosomal Variations" »

Fertilization Process

Ovulation occurs about fourteen days before menstruation. The egg released from the Graafian follicle is propelled along the fallopian tube to the uterus, taking over a week for this journey.

The egg can be fertilized for only 24 hours after ovulation while traveling along the fallopian tube.

Intercourse, or the sexual act, is the introduction of the penis into the vagina. At ejaculation, sperm are released inside the vagina.

Unlike the egg, sperm are very fast. They ascend through the vagina, traverse the cervix and uterus, and reach both fallopian tubes in a few hours. They can also survive for three to five days, so if intercourse occurs in the days before ovulation, the probability of pregnancy is very high.

If the egg... Continue reading "Fertilization and Early Pregnancy Stages" »

DNA Replication

DNA replication begins with the double helix unwinding, separating like a zipper. Each strand serves as a template for creating a new complementary strand. DNA polymerase enzymes add nucleotides one by one, matching adenine with thymine and guanine with cytosine. This process creates two identical DNA molecules, each with one original and one new strand. Errors during replication can lead to mutations, which can be harmless, cause diseases, or contribute to evolution.

The Importance of Base Complementarity

Base complementarity is crucial for accurate DNA replication, ensuring that genetic information is passed correctly from parent to daughter cells. It also forms the basis of many molecular biology techniques.

Gene Expression:

1. Health and Disease

1.1. Definitions

Health: A state of complete physical, mental, and social well-being, not merely the absence of disease.

Disease: A change in health status, i.e., a temporary or permanent loss of physical, mental, and social well-being.

Quality of Life: The comfort level, happiness, and satisfaction in a person that allows them to act and feel positively about their lives. This depends on their physical and mental health, their level of independence, and social relationships. One of the main indicators is life expectancy at birth.

1.3. Genes, Lifestyle, and Health

There are genetic diseases due to alterations in the genome (e.g., Down syndrome, hemophilia, or certain types of diabetes).

In other cases, the genotype determines... Continue reading "Health, Disease, and Infectious Diseases: A Comprehensive Overview" »

Types of Illness

There are several types of illness:

• Physical illness: Caused by injury, infection, or a degenerative process of the organism.
• Mental illness: May result from a malfunction of the brain.
• Social diseases: Can be caused by the existence of a violent social environment.

Defining Health and Illness

Health is a state of complete physical, mental, and social well-being. Illness is the state in which a person's health is disturbed.

Violence: Impact on Health and Society

Violence is a detrimental social issue, often originating in childhood. It negatively influences health, potentially harming or causing the death of loved ones, family members, or neighbors.

Understanding Infectious Diseases

Infectious diseases are caused by pathogens (such as... Continue reading "Foundations of Health: Diseases, Risks, and Well-being" »

Population Autoregulation

A population is constituted by a set of individuals of the same species living in a given location. Environmental resistance is a set of factors that prevent a population from reaching its maximum biotic potential. These factors include:

• External factors: These may be biotic (predators, parasites) or abiotic (climate change, food shortages, disasters, etc.).
• Internal factors: Increasing population density adversely affects individuals.

There are two forms of reproduction strategies:

• r strategists: These are simple organisms with very high biotic potential. They have many offspring with no parental care. Consequently, only a few manage to survive and reach adulthood. The population size remains relatively stationary (e.g.

Industrial Composting Processes

Compost is created through a biological process, relying on aerobic fermentation (with air). This technique ensures hygienic processing of organic waste into a homogeneous substance easily assimilated by the soil. The process involves a microbial population, including bacteria, actinomycetes, and fungi (responsible for 95% of the activity), as well as algae, protozoa, and cyanophytes.

Suitable Organic Materials for Composting

• Plants from the garden or orchard
• Adventitious herbs or "weeds" (before they seed)
• Poultry manure and bedding
• Lawn clippings (in thin, dried layers)
• Organic food remains
• Napkins and tissues (unprinted and uncolored)
• Haircuts (undyed)
• Raw wool or old mattresses (in small, mixed layers)
• Wine, vinegar,