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

Exception to the Cell Theory: Viruses

Is a self-replicating biological entity capable of using cellular machinery. It is a potentially pathogenic agent composed of a capsid protein surrounding the nucleic acid, which can be DNA or RNA. This structure can, in turn, be surrounded by the viral envelope, a lipid layer with different proteins, depending on the virus's life cycle. A virus always needs the metabolic machinery of an invaded cell to replicate its genetic material, producing many copies of the original. This process underlies the destructive power of viruses because they can damage or destroy the cell.

Features of Viruses:

• Size: Extremely small.
• Crystallization Structure: Having a volume and identical form, viral particulates tend to order

Angiosperms: The Flower

1. Floral Peduncle: The peduncle is the stalk that connects the flower to the plant.

2. Floral Receptacle: The receptacle is the expanded end of the peduncle where the floral parts (whorls) are attached. These include the calyx, corolla, androecium, and gynoecium.

Calyx

3. Sepals: The calyx consists of sepals, which are modified leaves that protect the developing flower bud.

Gynoecium (Female Reproductive System)

4. Ovary: The ovary contains one or more ovules (seminal primordia). Each ovule is attached to the ovary wall by a short stalk called the funiculus. The region where the ovule is inserted is called the placenta.

5. Carpels: The gynoecium is composed of one or more carpels, which are fused, bottle-shaped structures.... Continue reading "Understanding Angiosperm Flower Anatomy and Reproduction" »

Male Reproductive System

Glands Attached

• Seminal Vesicles: These two glands produce 60% of the seminal fluid, which contains fructose. They generate peristaltic contractions in the ejaculatory ducts. The clotting proteins in the semen form a weak coagulum in the vagina, keeping the semen in the deeper regions.
• Prostate: Nut-shaped, it surrounds and is traversed by the urethra. Prostatic fluid contributes 13-22% of semen volume and contains calcium, phosphate ions, and a clotting enzyme. The prostate's volume can increase with age (benign prostatic hyperplasia). Symptoms include increased prostate volume, difficulty urinating, and post-urination dribbling.
• Cowper's Glands: These glands clear the urethra of residual urine before sperm ejection. They

Human Reproduction

Sexual Reproduction

• Egg + sperm = zygote
• Viviparous development inside the mother

Sexual Reproduction includes:

• Gamete production methods
• Fertilization: zygote
• Development of the zygote: embryo
• Childbirth
• Child Development: Adult

Stages of Sexual Maturity

Children: Birth-10 years

• Primary sex characteristics

Puberty: 10-11 years

• Develop secondary sexual characteristics
• First menstruation
• Production of sperm

Adolescence

• The body prepares for reproduction

20-23 years

• Adult: end of development

Female Reproductive System and Gametes

Female internal organs:

• Ovaries: matures the egg
• Fallopian tube: connects ovary and uterus
• Vagina: connects the uterus to the outside
• Clitoris: sensitive due to a high number of nerve endings
• Labia minora: lines the external

Pelvis and Leg Bone Anatomy Q&A

1. Which bones form the pelvic girdle?
   The pelvic girdle is formed by the two innominate bones (hip bones), the sacrum, and the coccyx.
2. What is the pubic symphysis?
   It is the cartilaginous joint connecting the left and right pubic bones.
3. Which bones fuse to form the innominate (hip) bone?
   The ilium, ischium, and pubis fuse to form each innominate bone.
4. What is the function of the iliac crest?
   It serves as an important attachment point for abdominal and hip muscles.
5. Where does the femoral head articulate with the innominate bone?
   The head of the femur articulates within the acetabulum, a socket on the innominate bone formed by the fusion of the ilium, ischium, and pubis.
6. What is the function of the greater and lesser trochanters

Drug Tolerance and Dependence

1. In the stage of tolerance to the drug involved, the following are present in the nucleus: cAMP, protein CREB, dynorphin, and specific genes.
2. For the fight-or-flight response, both predominantly sympathetic activity and inhibited digestion occur.
3. Synaptic efficiency is incorrect; it increases the activity of presynaptic transporters.

Motor Control and Spinal Cord Injuries

4. If a rat makes a hemisection of the reticulospinal tract from the motor cortex (right side) at the bridge, the rat may not move the muscles on the left side of its body.
5. If you would like to block the action of cocaine in reward circuitry, you should inhibit dopamine receptors in the nucleus accumbens.

Alzheimer's Disease

6. In an old man with advanced Alzheimer'

Crohn's Disease

Crohn's disease is an inflammatory condition of unknown cause, frequently affecting the ileum in young adults. It causes severe diarrhea with a tendency towards fistulization. It is also known as regional enteritis or terminal ileitis.

Clinical Manifestations

Acute Ileitis

Often confused with appendicitis, acute ileitis occurs in children and adolescents.

Chronic Form

• Insidious onset with diarrhea and fever
• Palpable mass
• Fistulas (20% of cases)

General Symptoms

• Pallor
• Depression
• Erratic polyarthritis

Treatment

Treatment involves a combination of medical and surgical approaches.

Acute Pancreatitis

Concept

Acute pancreatitis is an aseptic inflammation of a necroticohemorrhagic nature. It involves autodigestion of the gland by its own enzymes,... Continue reading "Crohn's Disease, Pancreatitis, and Liver Conditions: Symptoms and Treatment" »

Regulation of Secretion in the Adrenal Cortex

The adrenal cortex is primarily controlled by the hypothalamic-pituitary axis. However, other mechanisms also influence the release of adrenal cortical hormones.

Negative Feedback

The primary feedback mechanism involves the hormone cortisol and its derivative, cortisone. An increase in cortisol levels inhibits Adrenocorticotropic Hormone (ACTH) secretion, while a decrease stimulates it. An excess of cortisol also leads to a decrease in Corticotropin-Releasing Factor (CRF).

Circadian Rhythm

The levels of adrenal cortical hormones are dependent on the circadian rhythm. Cortisol, in particular, exhibits a pronounced circadian rhythm, with the highest levels in the morning and the lowest at night. This rhythm... Continue reading "Adrenal Cortex Hormone Secretion and Regulation" »

Animal Kingdom: Invertebrate Zoology Review

Please review this questionnaire at home. Do not bring it on the day of the exam.

1. All animals are:
   • Autotrophs
2. Which of these animals has radial symmetry?
   • A sea anemone
   • A butterfly
   • A rabbit
   • A snail
3. An animal has bilateral symmetry if…
   • One line can be drawn to divide the animal into halves that are mirror images.
4. How does a cnidarian capture prey?
   • By paralyzing prey with venom.
5. How are coral reefs created?
   • From the skeletons of dead corals.
6. Which of these is a phylum of worms?
   • Annelida
7. Which of these characteristics is shared by all worms?
   • They have a brain.
8. Which of the following describes the feeding behavior of cnidarians?
   • They are carnivores.
9. The bodies of cnidarians have:
   • Radial symmetry.
10. What do earthworms do to soil?

Fixism

This theory proposes that species do not change; they remain unchanged from their creation. Linnaeus was a proponent of this thought.

Catastrophism

Georges Cuvier proposed that land disasters had destroyed existing species, leading to the creation of new species.

Neutral Theory

This theory posits that chance variations occur in populations, where a mutant gene can be dispersed without any selective advantage.

Punctuated Equilibrium

This theory suggests that the absence of intermediate steps in the fossil record is not due to incompleteness, but rather that evolution sometimes occurs in "leaps."

Evidence of Evolution

• Morphological: Studying comparative anatomy helps to understand the similarities and differences of the same organ in different