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

Sensory receptors are responsible for perceiving infortion, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces a feeling.

Pelvis and Leg Bone Anatomy Q&A

1. Which bones form the pelvic girdle?
   The pelvic girdle is formed by the two innominate bones (hip bones), the sacrum, and the coccyx.
2. What is the pubic symphysis?
   It is the cartilaginous joint connecting the left and right pubic bones.
3. Which bones fuse to form the innominate (hip) bone?
   The ilium, ischium, and pubis fuse to form each innominate bone.
4. What is the function of the iliac crest?
   It serves as an important attachment point for abdominal and hip muscles.
5. Where does the femoral head articulate with the innominate bone?
   The head of the femur articulates within the acetabulum, a socket on the innominate bone formed by the fusion of the ilium, ischium, and pubis.
6. What is the function of the greater and lesser trochanters

Chemistry of Life

The universe is mainly composed of Hydrogen (H) and Helium (He). The Earth's crust is composed of Silicon (Si), Iron (Fe), Magnesium (Mg), and carbon (C). Living organisms form organic macromolecules. Oxygen and Hydrogen constitute 68-70% of living matter (Water = H₂O). Nitrogen (N) is part of proteins.

Properties of Living Beings

Living beings are complex materials that can interact with the world around them and reproduce.

Features

• Made mostly of Carbon and H₂O
• Their reactions inside cells are governed by the laws of physics and chemistry.
• They reproduce

Interaction with the Environment

Living beings evolve and react to external or internal stimuli, creating responses through the nervous and endocrine systems (hormones).

Nutrition

Living...

Brain Protection and General Composition

The brain is enclosed and protected by the skull. Beneath the skull, the meninges provide further protection, and Cerebrospinal Fluid (CSF) flows within this space to reduce friction and cushion the brain.

The brain consists of two main types of tissue: gray matter and white matter.

• Gray Matter: Primarily involved in processing information and generating responses. It has a cortical arrangement (forming the outer layer or cortex) and is also found in deeper clusters called nuclei.
• White Matter: Forms a large mass connecting different brain areas. The corpus callosum, a large white matter structure, connects the two cerebral hemispheres across the interhemispheric fissure.

Important functions are associated...

**Functions of the Cell**

• Nutrition: Through nutrition, cells obtain the energy they need to create and maintain their structures and perform other vital functions. The molecules from which they obtain materials and energy are nutrients such as water, minerals, oxygen, and organic molecules.
• Relationship: By using this function, cells perceive physical and chemical changes that occur in the environment that surrounds them.
• Reproduction: Using this function, cells originate and divide into new cells.

**Types of Cells**

• Prokaryotes: They are characterized by a lower degree of complexity and a smaller number of organelles. These are single-celled organisms.
• Eukaryotes: They are characterized by a complex organization with many different compartments

Fundamental Concepts in Genetics

Understanding genetics requires familiarity with key terminology related to DNA sequences, inheritance patterns, and individual characteristics.

Defining Genes and Genetic Makeup

• Gene

  A Gene is an entire nucleotide sequence determined along one side of the chromosome ladder. This sequence may code for proteins or be inhibited, depending on the program assigned to the cells bearing the chromosomes.

• Genotype

  The Genotype is the genetic content (specific genome) of an individual in the form of DNA. It can also be defined as the complete set of genes of an organism.

• Phenotype

  The Phenotype is the observable expression of the genotype in a given environment. Phenotypic traits include both physical and behavioral characteristics.

Sensory Receptors and Organs

Receptors gather outside information. Exterorreceptores are sensory structures that make up the organs.

Eye

The eye is composed of 3 layers: sclera, choroid, and retina. The eyeball contains aqueous liquid and vitreous. The cornea bends light, and the lens focuses images. The retina receives inverted pictures, and fotorreceptors convert images into impulses.

Ear

The ear has 3 parts: external ear, middle ear, and inner ear. It is responsible for hearing and balance.

Touch

The skin has two layers: epidermis and dermis. It contains various receptors for pressure, cold, heat, and contact.

Nose

The nose contains mucosa and pituitary, which are responsible for olfactory receptors and heating the air.

Taste

There are 4 flavors on...

Postovulatory Phase and Fertilization

The postovulatory phase comprises days 15 to 28 of the menstrual cycle. After the expulsion of the ovum, the follicle degenerates, fat accumulates, and it becomes the corpus luteum. The innermost layer of the uterus gradually thickens and acquires a spongy appearance with numerous glands and blood vessels to nourish a future embryo. If fertilization does not occur, around the 28th day, the thickened layer of the uterus, the endometrium, is destroyed and expelled, along with the remains of the unfertilized egg. This process produces a hemorrhage known as menstruation or a period.

If fertilization occurs, the innermost layer of the uterus remains swollen during pregnancy. The corpus luteum in the ovary continues...

Gametogenesis: The Egg and Sperm

Gametogenesis is the biological process that occurs in the gonads, where gametes are formed.

The Ovule (Ovogenesis)

The egg cell, or ovule, is approximately 0.1mm in diameter and is rounded, almost spherical, and immobile. Its cytoplasm contains nutrient reserves, the yolk, which will nourish the embryo during the first days until implantation in the uterus. Surrounding the plasma membrane are protective structures, from inside out: the zona pellucida and the corona radiata.

Spermatozoa (Spermatogenesis)

The sperm cell is small and elongated, about 5mm in diameter, and consists of the following parts:

• Head: Contains a small amount of cytoplasm with nutrient reserves, the nucleus at its anterior end, and an enzyme-