Plant Anatomy and Reproductive Biology Essentials
1. Shoot Apical Meristem (SAM) & Histological Theories
The SAM is a self-renewing group of cells at the tip of the stem that generates all above-ground organs.
Key Theories of Organization
- Apical Cell Theory (Hofmeister/Nageli): Suggests a single “master cell” at the tip governs all growth. True for algae and bryophytes, but not higher plants.
- Histogen Theory (Hanstein): Proposes three distinct layers:
- Dermatogen: Becomes epidermis.
- Periblem: Becomes cortex.
- Plerome: Becomes the central vascular cylinder.
Human Anatomy and Physiology Vocabulary Reference
Nervous and Endocrine System Terminology
- Neuron: A cell that transmits information by electrical and chemical signaling.
- Motor Neuron: A neuron that helps to create the ability to move.
- Nervous System: The bodily system that transmits signals and coordinates actions of the body.
- Network: A group of connected neurons that process information.
- Vertebrae: The small bones that together make up the backbone and surround the nerves of the spinal cord.
- Reflex: An involuntary and immediate movement in response
Male and Female Reproductive Systems Explained
Male Reproductive System
The male reproductive tract follows this path: Seminiferous Tubules, Epididymis, Vas Deferens, Ejaculatory Duct, Urethra, and Penis.
Testes and Scrotum
The testes are paired gonads suspended in the tunica vaginalis. The scrotum consists of skin, dartos muscle, superficial scrotal fascia, cremaster muscle, and tunica vaginalis. The dartos and cremaster muscles regulate testicular temperature (~35°C) for spermatogenesis. The testes are perfused by the testicular artery and drained
Read MoreHuman Anatomy and Biological Systems Reference
Nervous System (Sis. Nervios)
- Nervous System: The bodily system that transmits signals and coordinates actions of the body.
- Brain (Cervell): The large organ that controls bodily functions through the release of hormones or activating muscles.
- Motor: If a neuron is a motor neuron, it helps to create the ability to move.
- Nerve: A cordlike structure that enables the transmission of electric impulses through the nervous system.
- Network: A group of connected neurons that process information.
- Neuron: A cell
Understanding Viruses: Structure, Replication, and Biology
The Discovery of Viruses
- Dmitri Ivanovski discovered that a disease in tobacco plants was spread by liquid extracted from infected plants.
- Martinus Beijerinck named these tiny disease-causing particles “viruses,” the Latin word for poison.
- Wendell Stanley showed that viruses can be crystallized, concluding they are not truly alive.
- Viruses are defined as nonliving particles made of proteins, nucleic acids, and sometimes lipids.
Key Vocabulary
- Virus: A nonliving particle made of proteins, nucleic acids,