Notes, summaries, assignments, exams, and problems for Biology

Myth 1: Everything is an Adaptation Produced by Natural Selection

We tend to assume that all characteristics of plants and animals are adaptations that have arisen through natural selection. Many are neither adaptations nor the result of selection at all.

Argument 1: Not everything is an adaptation

→ Male nipples

Argument 2: Multi-Skilled Genes

We have multi-skilled genes which have more than one function.

Myth 2: Natural Selection Is the Only Means of Evolution

Before we were told all of the 10 facts were myths, we already thought this was not right, because science can also change evolution with the advanced technology we have nowadays.

Myth 3: Evolution Leads to Ever-Greater Complexity

→ No -. Evolution gets rid of what we don’t use (example:... Continue reading "Debunking Common Myths About Evolution" »

Transgenic Vaccines

Transgenic vaccines are vaccines in which an extracted gene from an organism is introduced into a unicellular organism's genetic code (a bacteria or yeast). This is done to produce a certain protein (the one from the extracted gene) and to multiply that bacteria and the production of the protein in larger quantities. That protein is then able to produce the weakened protein of the membrane of the virus.

Steps of Production

The gene is extracted from the organism and introduced into the seed of the plant, meaning it's introduced inside the first genetic information of the plant. Then you need to plant the seed and allow for the production of the protein.

Advantage of Transgenic Vaccines by Yeasts Over Injured Viruses

They stimulate... Continue reading "Introduction to Biotechnology and Evolution" »

Real and Apparent Origins

Cranial nerves have a real origin, which is the nucleus of gray substance inside the brain, except for cranial nerves I, II, and VIII, whose real origin is outside the brain. The apparent origin is the attachment surface of the brainstem.

Specific Cranial Nerves

Olfactory Nerve (CN I)

Origin: Roof of the nasal cavity.

Optic Nerve (CN II)

Origin: Ganglionic cells of the retina.

Oculomotor Nerve (CN III)

Origin: Sulcus on the medial side of the cerebral peduncle.

• Superior division: Supplies the superior rectus and levator palpebrae superioris.
• Inferior division: Supplies the medial rectus, inferior rectus, and inferior oblique muscle.
• Function: Parasympathetic innervation, constricts the pupil via the ciliary ganglion.

Trochlear

Functions of the Blood

Transports nutrients and oxygen to all the cells and collects waste products produced by cell metabolism. Contributes to the regulation of body temperature. Plays a role in the fight against infections.

Cardiovascular System

Shares nutrients and oxygen between cells and collects waste products that cells produce during metabolism.

Puberty begins with the first ejaculation (spermache) and the first menstruation (menarche).

-Menopause (50), andropause (50)

Reproductive Tract

• Epididymis: Formed by the seminiferous tubes, where sperm mature.
• Ductus referens: Continuation of the epididymis and ascends up to the abdomen. It is used to store sperm.
• Urethra: Also part of the urinary tract connecting the bladder to the exterior.

Accessory Glands

• Seminal vesicles: Flow into ductus deferens, secrete spermatic fluid.
• Prostate: Secretes prostatic fluid which consists of substances to protect sperm from the acidity of the vagina.
• Cowper's glands: A pair of glands that secrete a lubricating fluid that facilitates sexual intercourse.

Reproductive Tract

• Fallopian tubes: Two small tubes located

1. Sensory Receptors

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

1.1. Types of Sensory Receptors

Sensory receptors can be classified according to the stimuli that they can receive, or by where they are located.

1.1.1. According to the Stimuli

• Photoreceptors: They detect light stimuli and are located in the eye.
• Mechanoreceptors: They are stimulated by mechanical changes such as pressure, contact, or sound waves.
• Chemoreceptors: They respond to chemical changes.
• Thermoreceptors: They detect temperature changes.

1.1.2. According to Their Location

• Internal receptors: They are located in the internal organs where they collect information

Muscle Fiber

Elongated cells that make up skeletal muscle tissue

Striation

Light and dark stripes in which skeletal muscle fibers are grouped

Fascicle

Dense bundles in which skeletal muscle fibers are grouped

Voluntary Muscle

Muscle that are consciously controlled

Involuntary Muscle

Smooth muscles that cannot be consciously controlled

Myofibril

Thread-like structures found in skeletal muscle fiber

Myosin

Thick filaments that make up myofibril

Actin

Thin filaments that make up myofibril

Z Line

Structure to which actin filaments are anchored

Sarcomere

The region from one Z line to the nerve

Tendon

Fibrous connective tissue that attaches muscles to bone

Flexor

Muscle that bends a joint

Extensor

Muscle that straightens a joint

Muscle Fatigue

Physiological inability of a

Lymphatic System: Components and Functions

The lymphatic system is composed of lymph, lymphatic vessels, lymphatic organs, lymphatic tissues, and lymph nodes.

Key Components of the Lymphatic System

Lymph

Lymph is a transparent liquid composed of lymphocytes and interstitial plasma that is formed when blood plasma is filtered as it travels to the tissues.

Lymphatic Vessels

Lymphatic vessels are closed at one end. Lymphatic capillaries are found in tissues, and they join into bigger conduits known as lymphatic veins that eventually connect with blood veins.

Lymphatic Organs and Tissues

Lymphatic organs and tissues perform several functions, such as producing and maturing lymphocytes and purifying blood. The most important lymphatic organs are the spleen... Continue reading "Human Body Systems: Lymphatic, Excretory, and Urinary Functions" »

Core Principles of Photosynthesis

The Light-Dependent Reactions

1. When oxygen is released during photosynthesis, what is it a direct by-product of?

   It is a direct by-product of splitting water molecules.

2. What is the role of pigment molecules in a light-harvesting complex?

   Within the thylakoid membranes, they absorb and transfer light energy to the reaction-center chlorophyll.

3. What is directly associated with photosystem I?

   It is directly associated with receiving electrons from the thylakoid membrane's electron transport chain.

4. How can one detect the lack of photosystem II in certain photosynthetic organisms?

   The most effective method is to test for the liberation of O2 in the presence of light, as photosystem II is responsible for splitting water to

Fundamental Knowledge Challenge

Earth Science & Geology

Formation of Smooth Stones

Which of these is the best explanation of how a smooth, round stone becomes smooth? It was in a stream for a long time.

Key Processes of the Water Cycle

Processes of the water cycle include: Evaporation, condensation, sublimation, and so on.

Formation of Water Droplets

The process by which water droplets form is: Condensation.

Astronomy & Physics

Defining Astronomical Bodies

Any astronomical body that revolves around a larger body is called a: Satellite.

Understanding Friction

Friction is the force that: Opposes motion between two surfaces.

Measuring Liquid Resistance to Flow

When scientists measure a liquid's resistance to flow, they are measuring its: Viscosity.

Biology