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

Plants and Their Importance

Plants play a vital role in maintaining life on the planet, and they also have great commercial value. They are multicellular eukaryotes and autotrophs. They contain chlorophyll, release oxygen into the atmosphere, and produce wood, charcoal and paper.

Plant Cell Structure

A plant cell consists of a cell wall, vacuoles, plastids, a nucleus and a membrane.

• Chloroplast: contains chlorophyll structures.
• Leucoplast: structures that store starch.
• Chromoplasts: pigment structures that give yellow or red (orange) colors.

Plant Tissues

• Growth tissue (meristem): responsible for plant growth. It is found at the tips of roots and stems.
• Support tissue: gives firm organization to the roots, stems and leaves, providing support and protection.

Genomics and Cloning Vectors

Genomic Libraries

A genomic library is a set of clones, each of which contains a fragment of a genome of a given organism.

Cosmids

Cosmids are cloning vectors which have been widely used in the preparation of large-sized genomic DNA libraries, allowing the introduction of DNA inserts up to 45 kb.

Yeast Artificial Chromosomes (YACs)

Yeast Artificial Chromosomes (YACs) are part of cloning vectors that maintain high capacity; in fact, they have the highest capacity (200 kb - 3,000 kb). A YAC is a vector meant to mimic the characteristics of a normal chromosome of a yeast (eukaryote), carrying a centromere and telomere terminals.

Expression Vectors

An expression vector is a bacterial or yeast plasmid used to produce clones...

Feedback Mechanisms in Biological Systems

1. Negative Feedback (Retroalimentación Negativa): It is one of the most common mechanisms to exert chemical regulation, where the final product of a chemical reaction inhibits the reaction that gave it origin.

2. Positive Feedback (Retroalimentación Positiva): The allosteric effect of the interaction of the metabolite with the primary reaction does not always have to be an inhibitor. A configuration change could also increase the reaction; i.e., the accumulation of the final product could accelerate the reaction from which it comes.

Homeothermic Animals

These animals have a very constant and usually high internal body temperature. The primary source of heat in them originates inside the cells of the...

Photosynthesis and Cellular Respiration

Key Biological Terms

• Photosynthesis: Only occurs in plants and some bacteria. It is the process in which autotrophs convert light energy into chemical energy.
• Respiration: The process in which cells make ATP by breaking down organic compounds. It occurs in both autotrophs (plants) and heterotrophs (animals).
• Autotrophs: An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide, like plants, algae, and some bacteria. They are producers.
• Heterotrophs: Heterotrophs cannot make their own food, so they must eat or absorb it. For this reason, heterotrophs are also known as consumers. Consumers include all animals, fungi, and many protists and bacteria.

Nervous System and Plant Responses

Reflex Action Versus Walking

Question: Differentiate between reflex action and walking.

Answer: A reflex action is an involuntary action, which is a rapid and automatic response to stimuli. In contrast, walking is a voluntary action which requires our thinking and is under our control.

Synaptic Transmission

Question: What happens at the synapse between two neurons?

Answer: A synapse is the microscopic gap between two neurons. At the synapse, the electrical signals are converted into chemical messengers (neurotransmitters) that can easily cross over the gap and pass on to the next neuron, where they are again converted into electrical signals.

Brain Function

Posture and Equilibrium

Question: Which part of the brain...

Classification of Living Organisms into Three Domains

Living organisms were originally divided into five kingdoms based on the presence of certain structural features. In 1978, this system was refined to account for clear biochemical differences between living organisms, specifically differences in rRNA sequences. According to the three-domain classification scheme, there are three distinct types of cellular organisms to which all living things belong:

• Eukarya: Contain a membrane-bound nucleus (includes plants, animals, protists, and fungi).
• Eubacteria: Lack a nucleus and consist of the traditional or 'true' bacteria (e.g., most pathogenic forms, E. coli, S. aureus, etc.).
• Archaea: Lack a nucleus and consist of the extremophiles or 'ancient' bacteria

The Monocyte-Macrophage System

Monocyte Development and Function

• Origin: Monocytes are formed in the bone marrow.
• Morphology: They possess a characteristic kidney-shaped nucleus.
• Circulation: They circulate in the blood for 72 hours before migrating through capillaries into tissue spaces.
• Maturation: Within 8 hours, they swell, increase in size, and develop a large number of lysosomes to become tissue macrophages.
• Systemic Role: Once they become tissue macrophages, they do not return to circulation. As both monocytes and tissue macrophages are phagocytic, they constitute the monocyte-macrophage system.

Mechanisms of Synaptic Plasticity

Presynaptic Mechanisms

1. Calcium Concentration: High-frequency stimulation of the presynaptic neuron leads to an accumulation

Darwin's Origin of Species and Natural Selection

In On the Origin of Species by Means of Natural Selection, Darwin sets out evidence that supports the theory of the evolution of species based on the role played by the mechanism of natural selection.

Natural Selection Summarized

Evolution by natural selection can be summarized in four points:

1. High reproductive capacity. Most species have a large reproductive capacity (alta capacidad reproductiva).
2. Struggle for existence. Population growth is limited by available resources, so individuals enter into a struggle for existence (lucha por la existencia).
3. Individual variability. There is considerable individual variation; some individuals have characteristics that differentiate them from the rest.
4. Survival

1. The Chemical Composition of Living Matter

Living matter is composed of approximately 20 of the 90 elements found in nature. Contrary to the Earth's crust, which is rich in silicon and aluminum, living organisms are primarily composed of hydrogen, carbon, oxygen, and nitrogen. Water is the primary medium for these elements. Other essential elements, such as iron, potassium, selenium, and sulfur, are present in trace amounts but are vital for survival.

2. Energy for Life

Life requires both matter and energy. Energy is obtained through chemical reactions involving inorganic matter, primarily synthesized via photosynthesis in plants and algae. To release the energy necessary for life, organisms perform cellular respiration. Based on how they obtain...

Lymphoid System Histology Assessment

1. White Pulp Composition

Which of the following cell types defines the white pulp in the spleen?

Incorrect Option Provided: B) Fibroblasts.

2. Tonsil Tissue Composition

Which of the following tissues is not found in the tonsils?

Incorrect Option Provided: A) Loose connective tissue.

3. Lymph Node Statement Evaluation

Which of the following statements about the lymph node is incorrect?

Incorrect Statement: E) The core area is characterized by fenestrated capillaries.

4. Thymic Epithelial Cell Function

Which feature and function is not peculiar to thymic epithelial cells?

Incorrect Function: B) Actively synthesize collagen and reticular fibers.

5. Hematotymic Barrier Function

What can be said regarding the hematotymic...