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

Origin of Life Hypotheses

The Oparin-Haldane hypothesis suggests that life arose gradually from inorganic molecules, with "building blocks" like amino acids forming first and then combining to make complex polymers.

The primitive atmosphere was reducing, containing water vapor and ammonia.

Both Oparin and Haldane proposed that the first life forms were heterotrophs.

Oparin's Work with Coacervates

Oparin's work with coacervates confirmed that enzymes fundamental for the biochemical reactions of metabolism functioned more efficiently when contained within membrane-bound spheres than when free in an aqueous solution.

Haldane's Primordial Soup Idea

Haldane's ideas about the origin of life were very similar to Oparin's. Haldane proposed that the primordial... Continue reading "Origin of Life: Oparin-Haldane & Miller-Urey" »

The Role of the Placenta in Mammals

The placenta is the organ from which our group of mammals takes its name: it is the main reason we, the placental mammals, are so much more successful than other mammals. The placenta is composed of several layers of material. It is very richly supplied with blood vessels. In this way, white blood cells and other immune system components are kept within the boundaries of their own systems while nutrients are allowed to pass in, and waste products to pass out, of the embryo's environment. There are at least five different forms the placenta can take in different species of mammals.

Blood Composition and Components

Plasma is the liquid component of the blood. It contains nutrients, wastes, salts, and proteins.... Continue reading "Mammalian Physiology: Placenta, Blood, and Vital Systems" »

These are energetic and structural substances found in many foods that we eat daily. There are two groups:

Simple Carbohydrates

• Monosaccharides: They are the simplest ones.
• Disaccharides: They are formed by two monosaccharides joined together.

Complex Carbohydrates (Polysaccharides)

They are neither sweet nor crystalline and they are not soluble in water. They include:

• Starch: It is made up of glucose molecules.
• Cellulose: It makes up vegetal fibre and forms the plant cellular wall. It is also made up of glucose molecules.

Inorganic Substances

These are small inorganic substances with variable composition. In solid state, they are structural. In dissolution, they are regulatory and allow our organs to function correctly and intervene in the regulation.... Continue reading "Energetic and Structural Substances in Foods" »

Pituitary

• Location: Head 2 lobes - anterior lobe
• Hormone: growth hormone
• Target organ: Whole body, skeleton
• Function: stimulate the growth

• Location: Head 2 lobes - anterior lobe
• Hormone: Thyroid stimulating hormone (TSH)
• Target organ: Thyroid
• Function: stimulate production of thyroid hormones

• Location: Head 2 lobes - anterior lobe
• Hormone: Gonadotropes. Follicle stimulating hormone (FSH) Luteinizing hormone (LH)
• Target organ: Ovaries and testes
• Function: action ovaries and testes

• Location: Head 2 lobes - anterior lobe
• Hormone: Adrenocorticotropic hormone (ACTH)
• Target organ: Adrenal glands
• Function: Stimulate the secretion of adrenal glands

• Location: Head 2 lobes - anterior lobe
• Hormone: Prolactin
• Target organ: breasts
• Function: stimulates breast growth and milk

Ectoparasites: True or False Statements

Test your knowledge on ectoparasites with these statements:

• Ectoparasites do not produce skin lesions. False (Many ectoparasites, like scabies mites, cause significant skin lesions.)
• Skin appendages are infested by ectoparasites. True (This includes hair, sebaceous glands, and sometimes nails.)
• Infestation by head and body lice refers to Bediculosis. False (The correct term is Pediculosis.)
• Hair and sebaceous glands are parts that can be affected by ectoparasites. True
• Ectoparasites are considered organisms. True (They are living organisms that live on the exterior of a host.)
• Many reports of ectoparasitic diseases have disappeared. False (Ectoparasitic diseases remain prevalent globally.)
• Scabies are not found

Enzyme Function and Segregation

1. What is the function of amylase? What is the function of pepsin? Why are they segregated?

• Amylase: Amylase begins the digestive process by breaking down starch when you chew your food, converting it into a smaller carbohydrate.
• Pepsin: Pepsin helps digest the proteins in food.

They are segregated because amylase functions primarily in the mouth (saliva), while pepsin functions in the highly acidic environment of the stomach.

Essential Digestive Terminology

2. Definitions:

• Chyme: Is the semi-fluid mass of partly digested food that is expelled by the stomach.
• Intestinal Flora: Is the symbiotic bacteria occurring naturally in the gut.
• Defecation: Is the final action of digestion, by which organisms eliminate solid, semi-

The Significance of Meiosis

Why Meiosis?

 Meiosis generates diversity by ensuring that the gametes it gives rise to will differ genetically from one another.

 Meiosis is unlike regular cell division, or mitosis, which produces daughter cells that are exact genetic copies of parent cells.

 Evolution is spurred on by differences among offspring, and meiosis and sexual reproduction ensure such differences.

 By contrast, asexual reproduction, as is seen in bacteria and other organisms, produces organisms that are exact genetic copies, or clones, of the parental organism.

 The genetic diversity brought about by Meiosis and sexual reproduction is responsible, to a significant extent, for the great diversity of lifeforms seen in the living... Continue reading "Understanding Meiosis: The Process of Genetic Diversity and Reproduction" »

Cell Structure and Membrane Transport

9) Which component is a microfilament (actin filament) of the cytoskeleton?

C

10) Which component is a glycolipid?

B

11) Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

12) Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

13) Which of the following allows water to move much faster across cell membranes?

Aquaporins

14) Diffusion _____.

Is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

15) Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas

Abiotic Levels of Organization

Subatomic Level

Composed of different particles (protons, neutrons, and electrons) that form atoms.

Atomic Level

Consists of atoms of the chemical elements from which living matter is formed. The different types of atoms are represented in the periodic table according to their number of protons within their nucleus. For example:

• Nitrogen
• Carbon
• Hydrogen
• Oxygen
• Phosphorus
• Sulfur

Molecular Level

Molecules are formed by the joining of two or more atoms. This level includes both inorganic and organic molecules.

Inorganic Molecules

• Water
• Gases
• Mineral salts

Organic Molecules

• Simple sugars
• Lipids
• Nucleotides
• Amino acids

Macromolecular Level

Macromolecules are formed when molecules join together. For example, proteins are formed when amino... Continue reading "Biological Organization: Levels of Life" »

1.Which of the Following processes is endergonic?

the Synthesis of glucose from carbon dioxide and water

2.What is the Basic difference between exergonic and endergonic reactions?

Exergonic Reactions release energy; endergonic reactions absorb it.

3.Which of the Following examples is classified as a metabolic pathway?

protein Synthesis

4.When a cell Uses chemical energy to perform work, it couples a(n) ________ reaction with A(n) ________ reaction.

exergonic . . . Endergonic

5.The transfer Of a phosphate group to a molecule or compound is called

phosphorylation.

6.Anything that Prevents ATP formation will most likely

result in Cell death.

7.The energy Required to initiate an exergonic reaction is called

the energy Of activation.

8.Most of a Cell's enzymes