Chemical and Cellular Basis of Life Practice Flashcards

Flashcards covering the chemical and cellular basis of life, including molecular biology, organelles, cell division, and metabolic processes based on the G12 Biology Resource Book.

What percentage of the ninety-two naturally occurring elements are considered essential for humans?

About 20-25\text{%}

Which four elements make up 96\text{%} of living matter?

Oxygen ($O$), Carbon ($C$), Hydrogen ($H$), and Nitrogen ($N$)

List the elements that make up most of the remaining 4\text{%} of the mass of an organism besides the primary four.

Calcium ($Ca$), Phosphorous ($P$), Potassium ($K$), and Sulphur ($S$)

What specific chemical bond type allows for the unique physical and chemical properties of water?

Hydrogen bonds

What is the bond angle of a water molecule?

$$104.5^\text{o}$$

Define cohesion in the context of water molecules.

Attraction between water molecules due to hydrogen bonding

How does water transport continuous columns through xylem against gravity?

Due to cohesion between water molecules and adhesion between water molecules and cell walls

At what temperature does water reach its maximum density?

$$4^\text{o}\text{C}$$

What property of water allows it to act as a thermal buffer in living systems?

High specific heat

Why does the solubility of solutes in water depend on polarity rather than their ionic nature?

Because water molecules surround each solute molecule and form hydrogen bonds with them based on charge distribution

What is the general formula for carbohydrates?

$$C_n(H_2O)_n$$

Which groups of carbohydrates are classified generally as sugars?

Monosaccharides and disaccharides

According to the transcript, how many carbon atoms vary in a monosaccharide?

From $3-7$

Identify the types of monosaccharides based on carbon count: $3C$, $5C$, and $6C$.

$3C$: Triose (e.g., Glyceraldehydes); $5C$: Pentose (e.g., Ribose, Deoxyribose, Ribulose); $6C$: Hexose (e.g., Glucose, Fructose, Galactose)

Name the three disaccharides mentioned and identify which one is non-reducing.

Maltose, Sucrose, and Lactose; Sucrose is the non-reducing sugar

What is the monomer and function of Chitin?

Monomer: Glucosamine; Function: Component of fungal cell walls and exoskeleton of Arthropods

What bond joins fatty acids to glycerol in a triacylglycerol molecule?

Ester bond

Distinguish between saturated and unsaturated fats based on their hydrocarbon chains.

Saturated fats have no double bonds and are mostly solid at room temperature; unsaturated fats have one or more double bonds and are mostly liquid

Which type of lipid is the major component of cell membranes?

Phospholipids

Describe the amphipathic nature of a phospholipid.

It has hydrophobic hydrocarbon tails and a hydrophilic phosphate group (head)

Name the central components of an amino acid molecule.

An asymmetric carbon atom, an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom ($-H$), and a variable $R$ group

What does 'amphoteric' mean in the context of amino acids?

Molecules that possess both alkaline (amino) and acidic (carboxyl) characteristics

Differentiate between the primary and secondary structures of proteins.

Primary structure is the unique sequence of amino acids linked by peptide bonds; secondary structure results from intramolecular hydrogen bonds forming alpha helices or beta pleated sheets

What five types of interactions maintain the tertiary structure of proteins?

$H$ bonds, disulphide bonds, ionic bonds, hydrophobic interactions, and Van der Waals interactions

Define denaturation.

The loss of a protein's specific three-dimensional shape due to the alteration of weak chemical bonds and interactions

Identify the three components of a nucleotide.

Pentose sugar, nitrogenous base, and a phosphate group

List the purines and pyrimidines found in nucleic acids.

Purines: Adenine ($A$) and Guanine ($G$); Pyrimidines: Thymine ($T$), Uracil ($U$), and Cytosine ($C$)

According to the Watson and Crick model, how many base pairs are in one complete turn of the DNA double helix?

Ten base pairs

What are the three types of RNA found in cells?

Messenger RNA ($mRNA$), Transfer RNA ($tRNA$), and Ribosomal RNA ($rRNA$)

What is the maximum magnification and resolution power of a light microscope?

Magnification: $1000\times$ actual size; Resolution: $0.2\text{μm}$

How do Scanning Electron Microscopes ($SEM$) differ from Transmission Electron Microscopes ($TEM$) in terms of usage?

$TEM$ is used to study internal cell structures using thin slices, while $SEM$ is used to observe surface views in three dimensions

State the three principles of the Cell Theory.

1. All organisms are composed of one or more cells. 2. The cell is the basic structural and functional unit. 3. All cells arise from pre-existing cells.

Compare the DNA of prokaryotes and eukaryotes.

Prokaryotic DNA is circular, lies free in the nucleoid, and lacks Histones; Eukaryotic DNA is linear, contained in a nucleus, and associated with Histone proteins

Who proposed the Fluid Mosaic Model of the cell membrane, and in what year?

Singer and Nicolson in $1972$

What is the role of cholesterol in the animal cell membrane?

To provide rigidity and stability to the membrane

Describe the structure of the nuclear envelope.

A double membrane (inner and outer) separated by a space of $20-40\text{nm}$, perforated by nuclear pores

What are the functions of the Smooth Endoplasmic Reticulum?

Synthesizes lipids (oils, steroids, phospholipids), metabolizes carbohydrates, detoxifies poisons, and stores $Ca^{2+}$ ions

Which organelle is responsible for collecting, modifying, packaging, and distributing proteins and lipids?

Golgi apparatus

Describe the arrangement of microtubules in cilia and flagella.

A $9 + 2$ structure (nine doublets in a ring with two single microtubules in the center)

Name the three types of cell junctions found in animal cells.

Tight junctions, Desmosomes (Anchor junctions), and Gap junctions (Communicating junctions)

What occurs during the $S$ phase of the cell cycle?

DNA replication and synthesis of histone proteins

Identify the five stages of Mitosis in order.

Prophase, Prometaphase, Metaphase, Anaphase, and Telophase

What is the difference between prophase I and prophase II in meiosis?

Prophase I involves synapsis and crossing over between homologous chromosomes, while prophase II involves the condensation of chromatin in haploid cells without further replication

Define metastasis.

The spread of cancer cells to locations distant from their original site

How much free energy is yielded when one mole of ATP is hydrolyzed?

$$-30.5\text{kJ/mol}$$

What is 'induced fit' in enzyme-substrate interactions?

The slight change in the shape of the active site so that the substrate and active site become complementary to each other upon interaction

Mention the primary differences between $C_3$ and $C_4$ plant leaf anatomy.

$C_3$ plants have photosynthesis in mesophyll cells; $C_4$ plants have Kranz anatomy where photosynthesis occurs in both mesophyll and bundle sheath cells

State the products of the link reaction (pyruvate oxidation) in aerobic respiration.

Acetyl Co-A, $CO_2$, and $NADH$

How much total ATP is generated from the oxidation of a single glucose molecule in active cells like heart or liver cells?

$$32\text{ATP}$$

What is the formula for the Respiratory Quotient ($RQ$)?

$$RQ = V_{CO_2} / V_{O_2}$$