Cellular Biology: Tension-Cohesion, DNA, Reproduction, and Cellular Evolution
The Tension-Cohesion-Adhesion Hypothesis
Tension-Cohesion-Adhesion Hypothesis:
- Mesophyll cells lose water, creating a water deficit in the top floor, which results in negative pressure, also known as tension. The solute concentration in these cells increases, consequently increasing the osmotic pressure.
- Mesophyll cells become hypertonic in relation to the xylem, drawing water molecules into the cells.
- Water molecules are linked together due to cohesion forces (between water molecules) and adhesion
Fundamental Concepts in Genetics and Biology
Mendel’s Laws
- All individuals descended from the cross of two pure races are equal.
- To cross each other, the character of hybrids present in these are separated and are combined at random in the descendants.
- The various characters are inherited independently of one another and are combined at random in the offspring.
Cloning
Cloning, in scientific language, describes the obtaining of an individual identical to another. We call it a clone, i.e., with the same genome. Plants and animals, such as the sponge,
Read MoreDarwin’s Theory and Evolution: Key Concepts Explained
Darwin’s Theory and Evolution: Key Concepts
1) The Importance of Darwin’s Theory: Darwin’s major development theories aimed to prove that life emerged, deviating from lower to higher forms. With the passage of time, this evolutionary process became more complex, causing better-adapted individuals to exist. Animals and plant species inhabiting the Earth are subject to change, and it is through these changes that new forms of development originate.
2) Evolution: The process of continuous change over
Read MorePlant Processes: Respiration, Photosynthesis, and Nutrition
Key Functions of Plant Parts
Leaves
Leaves exchange gases with the environment through the stomata. Both respiration gases and photosynthesis gases, including water vapor, are expelled through perspiration. The leaves perform photosynthesis. Leaf cells have many chloroplasts, which are the organelles where the transformation of inorganic into organic substances takes place.
Stem
The stem carries crude sap through the xylem tubes and the elaborated sap through the phloem. It also performs other functions
Read MoreRespiratory System: Structure and Gas Exchange
Human Respiratory System
Anatomy
Nose: Organ containing the nostrils, which are two cavities separated by a septum. These form the nasal cavity. The interior is lined with a mucous membrane containing hairs, cilia, and glands that produce mucus. The mucus moistens the air and filters out dust particles. The blood in the capillaries warms the air.
Pharynx or throat: Muscular tube connected to the nasal cavity and the mouth. It forms part of both the digestive and respiratory systems. It contains almond-
Read MoreStem Cells, Genetic Engineering, and GMOs: Key Concepts
Stem Cells: Types and Applications
1 – Embryo Cryopreservation: Embryos are frozen in liquid nitrogen at -160ºC. This process stops the vital functions of the embryo without causing death.
2 – Legal and Ethical Considerations in Spain: Spanish legislation prohibits choosing the sex or any other characteristics of children. However, embryo selection is permitted in specific cases, such as:
- To prevent genetic abnormalities in children: If a hereditary disease is sex-linked, the sex of implanted embryos