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

Fertilization

Fertilization occurs when a sperm and an ovum unite, forming a zygote. This process requires both ovulation and sexual intercourse. It's only possible during a 24-48 hour window after ovulation, although sperm can survive up to 5 days inside the female reproductive tract. The sperm penetrates the ovum's covering, and a fertilizing membrane forms, preventing other sperm from entering. The nuclei of the sperm and ovum join. After fertilization, the zygote travels to the uterus. The corpus luteum continues to release progesterone, maintaining the thick endometrium walls and preventing menstruation. During its journey, the zygote divides, becoming a ball of cells called a morula (around day 4) and then a blastocyst (around day 5).... Continue reading "Understanding Human Reproduction and Infertility" »

The Human Circulatory System

The circulatory system is responsible for the distribution of nutrients and oxygen throughout the body.

The elimination of carbon dioxide is primarily handled by the respiratory system, with the circulatory system transporting CO2 to the lungs.

Functions of the Circulatory System

• Distribute the nutrients from food and oxygen throughout the entire organism.
• Collect waste substances produced by cellular metabolism and transport them to the excretory organs.

Components of the Circulatory System

Blood

Blood is a red, viscous, and saline liquid which flows within blood vessels.

Blood Vessels

Blood vessels form a network of tubes through which blood circulates. These include arteries, arterioles, capillaries, venules, and veins.... Continue reading "Human Circulatory System: Structure, Function, and Components" »

Describe the location and Functions of the lateral occipital cortex (LOC), the fusiform face area (FFA) And the estrastriate body area (EAB).

The Lateral occipital complex (LOC) is a large region of the ventral stream of the Visual association cortex, and appears to respond to a wide variety of objects And shapes. // The fusiform face area (FFA) is located in the ventral stream, On the anterior fusiform gyrus. It recognizes facial features, but also the Activity of this region can be affected by previously learned information. // The Extraestriate body area (EBA) is located in the ventral stream posterior to the FFA and partly overlaps it. This region is specifically activated by Photographs, silhouettes, or stick drawings of human bodies or

Glossary of Genetics and Cell Biology Terms

Basic Genetic Concepts

Allele

A variant form of a gene.

Chromosomes

Threadlike structures made of DNA molecules that contain the genes.

DNA (Deoxyribonucleic acid)

A complex molecule containing the genetic information that makes up the chromosomes.

Gene

A segment of DNA on a chromosome that codes for a specific trait.

Genotype

The genetic constitution of an individual organism.

Phenotype

The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Trait

A specific characteristic of an organism.

Cell Division and Reproduction

Cell Reproduction

The process by which cells produce new cells. In many cases, this involves creating exact copies of the cells they

Gas Exchange

Blood is circulated to the lungs to obtain oxygen. This happens in the alveoli. Air entering the lungs has a higher concentration of oxygen and a lower concentration of carbon dioxide than the air that the lungs release. The blood exiting the lungs has a higher oxygen concentration and a lower carbon dioxide concentration than when it enters. The amount of nitrogen remains constant. Oxygen passes through the alveolar wall. These gases traverse the membrane of the cells by diffusion.

What Happens Inside the Alveoli?

The total surface area of the lungs' alveoli is enormous. Each alveolus is surrounded by many tiny blood vessels called capillaries, and the wall is extremely thin.

Microorganisms in the Air

Upper respiratory illnesses like... Continue reading "Human Biology: Respiration, Microorganisms, and Nutrition" »

The Endocrine System

The endocrine is made up of coordinated groups of glands called endocrine glands. They are called endocrine because they release hormones into the bloodstream.

Hormones

Hormones are chemical messengers that activate or stop, accelerate or delay many processes carried out by organs and tissues.

Health Diet (E.S)

Healthy diet, regulate moderate-intensity exercise, and don't consume drugs.

Health Diet

Healthy diet, exercise regularly, and practice correct postures.

The Control of Hormone Secretion

Feedback mechanisms in the endocrine system act similarly. When the amount of hormone in the blood reaches a specific level, a signal makes the gland stop releasing it.

How Hormones Work:

1. Stimulated endocrine glands respond by producing hormones

Stages of Cell Division

Prophase: The first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears. The first prophase of meiosis includes the reduction division.

Metaphase: The second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers.

Anaphase: The stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle.

Telophase: The final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytokinesis: The cytoplasmic division of... Continue reading "Cell Division, Reproduction, and Biological Processes" »

Genetics Terminology

Basic Concepts

• Trait: An inheritable characteristic of an organism.
• Gene: A DNA segment containing information that controls a specific trait.
• Allele: A variant form of a gene, often arising from mutations, contributing to hereditary variations.
• Locus (pl. Loci): The specific location of a gene on a chromosome.

Zygosity

• Homozygous Organism: Possesses identical alleles for a given gene (e.g., AA or aa).
• Heterozygous Organism: Possesses different alleles for a given gene (e.g., Aa).

Allele Interactions

• Dominant Allele: An allele that expresses its phenotype regardless of the paired allele.
• Recessive Allele: An allele that expresses its phenotype only when paired with an identical allele.

Genetic Inheritance Patterns

• Dominance (Dominant

Genome

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" »