Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Xerophyte Adaptations

(Plants adapted to dry/arid environments – e.g., cactus, Opuntia)

1. Structural Adaptations

• Thick cuticle to reduce water loss.
• Sunken stomata to trap moisture and reduce transpiration.
• Reduced leaves (spines) to minimize water loss.
• Thick stems that store water (succulent stems).
• Deep or widespread roots to access water from deeper soil layers.

2. Physiological Adaptations

• CAM photosynthesis (in some) to open stomata at night.
• High osmotic pressure to absorb water quickly.
• Fewer stomata in number or present only on the lower surface.

Hydrophyte Adaptations

(Plants adapted to aquatic environments – e.g., lotus, water hyacinth)

1. Structural Adaptations

• Thin cuticle or absent cuticle as water is abundant.
• Large air spaces (aerenchyma)

Nervous System Anatomy

• Functions:

  • Controls perception (sight, touch, hearing, taste).
  • Maintains homeostasis (e.g., blood pressure, body temperature).

• Divisions:

  • Central Nervous System (CNS): Brain & spinal cord (processes information and sends responses).
  • Peripheral Nervous System (PNS): Motor & sensory neurons connecting the CNS to the rest of the body.

• PNS Subdivisions:

  • Somatic Nervous System: Controls voluntary movement (e.g., moving hands).
  • Autonomic Nervous System: Controls involuntary functions (e.g., heart rate).
    • Sympathetic Division (Fight or Flight): Increases alertness, heart rate, etc.
    • Parasympathetic Division (Rest & Digest): Slows heart rate, promotes digestion, etc.

• Structural Differences (Autonomic):

  • Parasympathetic: Long preganglionic

1. Essential Atmospheric Layers

The troposphere and the stratosphere are the most important layers for life. The atmospheric structure includes:

• Troposphere: The lowest layer (contains the tropopause and ozone maximum).
• Stratosphere: Located above the troposphere.
• Mesosphere: Includes the mesopause.
• Thermosphere: The highest layer.

2. Primary Atmospheric Gases

The atmosphere is composed mainly of Nitrogen (78.9%) and Oxygen (20.95%). Other trace gases include:

• Argon: 0.93%
• CO2: 0.038%
• Traces of neon, helium, methane, water vapor, krypton, hydrogen, xenon, and ozone.

3. Climate Influencing Factors

The two abiotic factors that influence climate the most are temperature and moisture.

4. Solar Radiation Distribution

Solar radiation reaching Earth is either reflected...

Cellular Development Stages

The early stages of development occur at the cellular, tissue, and organ levels of organization. At the cellular level, development includes cleavage, resulting in a multicellular embryo and the formation of a blastula.

Cleavage, which encompasses DNA replication and mitotic stages, is cell division without growth and results in a morula, a ball of cells. The next cellular stage is the formation of a blastula, a hollow ball of cells with a fluid-filled cavity called a blastocoel. The blastocoel forms when the cells of the morula pump Na+ into extracellular spaces, and water follows by osmosis.

Tissue Development Stages

The tissue stages of development are the early gastrula and the neurula. The early gastrula stage begins...

Aquatic Respiration: Understanding Gills

Gills are highly effective respiratory structures adapted for life in water. They are laminar expansions formed by the filiform body wall of an animal. If these expansions project outside the body, they are called external gills. If they are housed inside a cavity that communicates with the outside, they are called internal gills.

External Gills: Simpler Respiratory Structures

External gills are evolutionarily the oldest, formed by expansions of the body surface. They occur in some mollusks, insects, and aquatic larvae of amphibians and crustaceans. However, they present several disadvantages:

• They are vulnerable to predators.
• They are easily injured.
• They can make movement difficult.
• Animals possessing these

Fundamental Tissue System

The fundamental tissue system provides structure, storage, and metabolic functions for the plant.

Parenchyma

Parenchyma is composed of living cells with large vacuoles and thin, strong cell walls. These cells typically cannot divide. Parenchyma carries out photosynthesis and stores substances. Several types are distinguished:

• Chlorophyll Parenchyma (Chlorenchyma): Found in leaves and green stems. Its cells contain chloroplasts and perform photosynthesis.
  • Palisade Parenchyma: Located on the upper side of leaves, constituted by elongated and tightly packed cells.
  • Spongy Parenchyma: Found in the interior and underside of leaves, formed by irregular cells that leave empty spaces (meatus or air spaces).
• Reserve Parenchyma: Found

1. Health and Disease

1.1. Definitions

Health: A state of complete physical, mental, and social well-being, not merely the absence of disease.

Disease: A change in health status, i.e., a temporary or permanent loss of physical, mental, and social well-being.

Quality of Life: The comfort level, happiness, and satisfaction in a person that allows them to act and feel positively about their lives. This depends on their physical and mental health, their level of independence, and social relationships. One of the main indicators is life expectancy at birth.

1.3. Genes, Lifestyle, and Health

There are genetic diseases due to alterations in the genome (e.g., Down syndrome, hemophilia, or certain types of diabetes).

In other cases, the genotype determines...

Obtaining Transgenic Organisms: The Process

In the first stage of processing, the desired gene needs to be introduced into the genome of a cell from the organism you wish to modify.

Stage 1: Gene Introduction and Preparation

1. All DNA is extracted from the cell into which the gene of interest will be transferred.
2. The gene is located, and the precise DNA fragment containing it is extracted by cutting.
3. The gene is cloned, as it is impossible to work with a single copy.
4. Other fragments are amended by adding exogenous genes to facilitate the subsequent reading of the formed recombinant DNA. This is sometimes referred to as goblins.
5. The transgene is introduced into the nucleus of the cell to be modified. For this, a vector is often used, which is typically