MDCAT Biology Practice Flashcards

Practice flashcards covering the introductory chapters of biology, including biomolecules, enzymes, cell structure, and the variety of life (viruses and viruses.

From which Greek words is the term 'biology' derived?

'Bios' (life) and 'Logos' (discourse).

According to the modern system of taxonomy, into which five kingdoms are living organisms classified?

Kingdom Prokaryotae (Monera), Kingdom Protoctista (Protista), Kingdom Fungi, Kingdom Plantae, and Kingdom Animalia.

What is the size range of bacteria compared to the dimensions of a Redwood tree mentioned in the text?

Bacteria may measure no more than $0.0001\,mm$, whereas Redwood trees can exceed $300\,feet$ in height.

How is 'Molecular Biology' defined in the lecture notes?

A branch dealing with the structure and function of molecules (like Nucleic acids and Protein molecules) that form cell structures and organelles involved in biological processes.

What is the definition of 'Biotechnology'?

A branch dealing with the use of data and techniques of engineering and technology for the study and solution of problems concerning living organisms, particularly human beings.

What is the smallest unit of an element that retains all its properties?

An atom.

What are the three categories of food or natural macromolecules recognized in living organisms?

Carbohydrates, lipids, and proteins.

Define 'Biosphere'.

The part of earth inhabited by living organisms, including both living and non-living components.

When is life postulated to have arisen in the world?

Almost two and a half billion years ago ($2.5\,billion$ years ago).

What is a 'phyletic lineage'?

An unbroken series of species progressing from ancestor to descendent, with each group evolving from the one immediately preceding it.

Who introduced the process of immunization by vaccination in 1795?

Edward Jenner.

Which scientists shared the 1945 Nobel Prize for the discovery, isolation, and large-scale production of penicillin?

Fleming, Florey, and Chain.

What is 'Hydroponics'?

The science of growing terrestrial plants in an aerated solution, also known as soil-less or water culture.

From which cell was 'Dolly' the sheep successfully cloned in 1997?

A somatic cell.

What percentage of the protoplasm's mass is typically water?

$70$ to $90\%$.H_2O$$

Which six elements make up about $98\%$ of the body weight of an organism?

Carbon ($18.5\%$), Hydrogen ($9.5\%$), Oxygen ($65\%$), Nitrogen ($3.3\%$), Phosphorus ($1.0\%$), and Sulphur ($0.3\%$).

In external or internal environments, what is the separation of electrical charge in a water molecule called?

A dipole.

What is 'condensation' (dehydration synthesis) in the context of macromolecules?

The joining of two monomers when a hydroxyl ($-OH$) group is removed from one and a hydrogen ($-H$) is removed from the other, resulting in the removal of a water molecule.

What was the name protein suggested by, and in what year?

Suggested by Berzelius in $1838$.

Describe the 'Tertiary Structure' of a protein.

The arrangement of secondary structure into a three-dimensional (fold or super fold) structure held by peptide, hydrogen, ionic, and disulphide bonds.

What is the ratio of hydrogen to oxygen in carbohydrates?

$2:1$ (the same ratio as in water).

What are 'Waxes' chemically?

Simple lipids having one molecule of fatty acid forming an ester bond with one molecule of long-chain alcohol.

How much energy is released during the conversion of ATP into ADP?

$31.81\,Kj$ or $7.3\,K.\,Cal/mole$.

Identify the nitrogenous bases classified as Purines.

Adenine ($A$) and Guanine ($G$).

What is the process of 'Transcription'?

The step where information contained in a specific segment of $DNA$ is copied into $RNA$ (specifically $mRNA$).

What did Euler (1932) propose concerning conjugated enzymes?

That a conjugated enzyme showing complete activity be called a 'holoenzyme'.

What is the optimum $pH$ for the enzyme pepsin found in the stomach?

$1.4$.

How do non-competitive inhibitors obstruct enzymatic reactions?

By binding to a part of the enzyme (allosteric site) away from the active site, causing the enzyme to change shape and making the active site unreceptive to the substrate.

What are the three points of the Cell Theory?

1. All organisms are composed of one or more cells. 2. The cell is the structural and functional unit of life. 3. Cells can arise only by division of pre-existing cells.

Distinguish between 'Phagocytosis' and 'Pinocytosis'.

Phagocytosis is 'cell eating' (ingesting solid particles), while Pinocytosis is 'cell drinking' (taking in liquid material in bulk).

Identify the three layers of a plant cell wall and their typical thicknesses.

Middle lamella, Primary wall ($1.3\,\mu m$ thick), and Secondary wall ($5-10\,\mu m$ thick).

Which organelle is known as the 'Power House' of the cell?

Mitochondria.

What are 'Lysosomes' and why are they called 'suicide sacs'?

Spherical bodies containing digestive enzymes; if their membrane ruptures, the enzymes destroy the cell by digesting its own proteins (autophagy).

What are the three types of cytoskeleton elements?

Microfilaments ($7\,nm$), Intermediate filaments ($8$ to $11\,nm$), and Microtubules ($25\,nm$).

Define 'Binomial Nomenclature'.

The system of giving each species a two-word name consisting of the genus (capitalized) and the specific designation (lower case), both in italics.

What is a 'Bacteriophage'?

A virus that infects bacteria, consisting of a $DNA$ molecule coiled within a protein head, a tail core, a base plate, and tail fibers.

Contrast the 'Lytic Cycle' and 'Lysogenic Cycle' of a virus.

The Lytic Cycle results in the death (lysis) of the host cell and release of phages, while the Lysogenic Cycle replicates the viral genome ($prophage$) without destroying the host.

What is the causative agent of AIDS?

$HIV$ (Human Immuno-deficiency Virus), which is a retrovirus.