All quizzes botany 2

In plant cells, the Mevalonic Acid (MVA) pathway for terpenoid biosynthesis is primarily located in which cellular compartment?

Cytosol

Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) are the fundamental 5-carbon precursors for all terpenoids. What is their chemical relationship?

They are structural isomers.

Glycyrrhizin, the intensely sweet primary active constituent of licorice root (Glycyrrhiza glabra), is chemically classified as a:

Triterpenoid saponin

The larger precursors for triterpenes and tetraterpenes are formed by dimerization, joining two smaller precursors together in what specific orientation?

Tail-to-tail

Enfleurage, a traditional labor-intensive extraction method using odorless animal fats, is specifically designed to extract which compounds from delicate flowers like jasmine?

Fragrant monoterpene essential oils

The for melvonate (MVA) pathway for terpenoid biosynthesis utilizes which molecule as the initial starting material for this pathway?

Acetyl-CoA

The methylerythritol phosphate (MEP) pathway for terpenoid biosynthesis utilizes which two molecules as the initial starting materials for this pathway?

Pyruvate and glyceraldehyde 3-phosphate (G3P)

What physical change occurs to heavy, non-volatile diterpenes when a resinous tree is injured?

They oxidize into a hard, glassy plug to seal the wound

What is the primary ecological function of the highly volatile monoterpenes (like pinene) emitted by many coniferous trees?

To defend against insect herbivores and fungal pathogens.

While enfleurage and steam distillation are common extraction methods for essential oils, which method is almost exclusively used to extract monoterpene-rich essential oils from citrus peels (like lemon and sweet orange)?

Cold pressing

Terpenoid Saponins are characterized by their "dual nature," meaning they are:

 

Amphiphilic (lipid-soluble backbone and water-soluble sugar)

Beta-carotene is a deeply pigmented tetraterpene. In human metabolism, beta-carotene is a crucial dietary precursor that is cleaved to form which essential nutrient?

Vitamin A

In prenylation, how are isoprene units (IPP and DMAPP) in terpenoids typically linked in which configuration?

Head-to-tail

Squalene is a crucial biochemical intermediate in plants and animals. It is a 30-carbon precursor that ultimately folds and cyclizes to form which important class of compounds?

Steroids and sterols

How many isoprene units make up the core aglycone in a diterpene glycoside?

4

Which physical property is the primary reason that monoterpenes and sesquiterpenes can be effectively extracted from plant material using steam distillation?

They are highly volatile and carry over with steam.

What is the fundamental five-carbon building block that makes up all terpenoid structures?

Isoprenes

Which specialized internal structures are used by plants like Frankincense and Pine to store heavy, less volatile oleoresins?

Secretory ducts (elongated canals)

How many isoprene units make up the core aglycone in a diterpene glycoside?

4

Where are essential oils most commonly synthesized and stored in plants like Peppermint or Lavender?

Glandular trichomes (epidermal hairs)

Which molecule acts as the primary 15-carbon precursor for sesquiterpenes?

Farnesyl pyrophosphate (FPP)

Why does inulin escape digestion by human enzymes like alpha-amylase in the upper GI tract, allowing it to pass intact into the colon?

Human amylase lacks the ability to cleave the specific beta (2→1)-glycosidic bonds linking the fructose molecules.

In addition to aiding in water retention during periods of drought, plants produce mucilages to assist with what other vital physiological process?

Seed germination (imbibition)

When a plant has excess energy from photosynthesis, it is converted into Glucose-1-phosphate and polymerized into starch inside which specific organelle?

Chloroplast

The physiological process of “gummosis” following a plant injury primarily involves what internal cellular event to produce the gum?

The enzymatic breakdown and conversion of the plant’s own cell walls.

When starches that escape the upper GI digestion are fermented by gut flora in the colon into which beneficial compounds?

Short Chain Fatty Acids (SCFAs)

Which polysaccharides are highly branched acidic polymers are primarily synthesized in the Golgi apparatus before being shipped outside the cell?

Mucilages and Pectins

What two primary roles does starch typically play when used as a vital excipient in pill manufacturing?

A binder to hold the tablet together and a disintegrant to break it apart once it is wet.

Acemannan, the primary bioactive polysaccharide found in Aloe vera, is a long-chain polymer primarily composed of which monomer?

Mannose.

What happens to the molecular structure of certain starches (like those in rice) when they are subjected to a cooking and subsequent cooling process?

The molecules undergo structural tight-packing, allowing them to escape upper GI digestion and enter the colon as resistant starch.

Why do demulcent mucilages act as an antitussive (cough suppressant) when ingested?

By physically coating the laryngeal mucosa and reducing sensory irritation of the vagus nerve.

Unlike starches and mucilages, plant gums are considered pathological products because they are produced primarily in response to what?

Injury, disease, or extreme environmental stress.

Where does the synthesis of long cellulose fibers occur within the plant cell?

At the plasma membrane vie Cellulose Synthase.

In the cytosol, if triose sugars (G3P and DHAP) are not used to synthesize nucleotide, sugars, they can be converted into which molecule for immediate energy from cellular respiration?

Pyruvate.

During the biosynthesis of complex polysaccharides, enzymes do not typically polymerize free glucose directly. Instead, where do enzymes like Cellulose Synthase derive the necessary thermodynamic energy to form new glycosidic bonds and elongate the polymer chain?

From the high-energy phosphate bonds of nucleotide sugars (such as UDPG, ADPG, or GDPG) that act as activated donors.

Plants significantly increase the production of mucilages in response to drought or saline stress primarily for what purpose?

To retain moisture and prevent water loss.

Unlike starches and mucilages, plant gums are completely insoluble in which of the following solvents?

a) Alcohol. b) Warm water. c) Vinegar. d) Cold water. e) Lipids

Alcohol

While amylose consists of linear chains of glucose, amylopectin is larger and contributes to the thickening properties of starch due to what structural feature?

Branching points created by alpha (1-→6)-glycosidic linkages.

What type of starch is a highly branched polymer containing both alpha (2→4) and alpha (1→6) glycosidic linkages?

Amylopectin.

What preparation method is preferred for obtaining clear, high-purity mucilages while leaving insoluble starch behind in the plant fiber?

Cold water maceration.

What is the primary physiological advantages for plants storing energy as semi-crystalline starch granules rather than as free sugars?

It allows for dense energy storage without affecting osmotic pressure.

The polymerization of ADP-Glucose (ADPG) results in the formation of starch, which is a mixture of which two distinct glucose polymers?

Amylose and Amylopectin.

Which of the following is NOT a listed function of phenolics in plants?

-Forming sporopollenin in the pollen wall.  

-Providing protection from UV light.

-Attracting pollinators with floral pigments and scent compounds.

-Facilitating primary photosynthesis and glucose production.

-Defending against herbivores and pathogens. 

Facilitating primary photosynthesis and glucose production

How do schisandrins (dibenzoclooctadiene lignins) actively promote the regeneration of damaged liver tissue?

By stimulating the hepatic production of glutathione and accelerating liver cell detoxification

What is the chemical backbone structure of true coumarins?

Benzo-alpha-pyrones

Some benzoic acids are referred to as pseudo tannins because they possess which specific properties?

Astringent properties of tannins

What is the most common type of linkage found in plant glycosides, connecting the sugar portion to the non-sugar portion?

O-glycosidic bond

How is poisoning from dicoumarol or warfarin, an anticoagulant, treated?

By administering vitamin K

Schisandrins are highly valued adaptogens noted for which primary therapeutic property?

Hepatoprotective (liver-protecting) properties

The bacterial or fungal modification of coumarins can form 4-hydroxycoumarin, which led to the development of which commercial product and pharmaceutical?

Warfarin (commercial rat poison and anticoagulant drugs)

Khellin, a furanochromone, is a diuretic and smooth muscle relaxant, but when applied topically and exposed to UV light, it causes what effect?

Pigmentation returns to treated areas

Furanocoumarins and furanochromones can stimulate melanogenesis when exposed to what environmental factor?

UV light

What structural classification best describes phenylpropanoids?

C6-C3

What structural classification best describes phenylethanoids?

C6-C2

Which of the following amino acids are produced via the Shikimic Acid Pathway and serve as precursors to many natural products?

• Serine and Cysteine.

• Glutamine and asparagine.

• Tyrosine, tryptophan, and phenylalanine.

• Lysine and arginine.

• Alanine and glycine.

Tyrosine, tryptophan and phenylalanine

Secoisolariciresinol, a lignan found in flaxseed, is metabolized by human gut bacteria into compounds that have what kind of effect?

Phytoestrogenic and hormone-modulating effects.

Simple coumarins are often responsible for which characteristic scent that forms after harvesting and drying certain plants?

A vanilla-like odor of newly mown hay.

Phenylpropenes are highly aromatic compounds that are commonly found as major components in which of the following?

Spices

True lignans are formed from two phenylpropanoid units (monolignols) that are typically linked together at which position?

The central carbon of their respective three-carbon side chains

Which class of coumarins is known to act as photosensitizing agents and cause phytophotodermatitis?

Furanocuomarins (Psoralens)

What structural classification best describes phenolic acids?

C6-C1

Coumarins were first isolated in 1820 from which plant source?

Tonka bean (kumaru)

Which class of plant compounds acts as a photosensitizing agents and is known to cause phytophotodermatitis?

Furanocoumarins (Psoralens)

Plant defensins possess positively charged surfaces that are attracted to the negatively charged components of which organisms’ membranes?

Bacteria and fungi

How does the overarching structure of a plant defensin fundamentally differ from that of a cyclotide?

Defensins are linear (open-ended) rather than existing as a closed cyclic ring.

What is the traditional method for preparing cyclotide-rich medicines, taking advantage of their exceptional stability?

Hot-water decoctions

Lectins are large, non-immune proteins or glycoproteins that act as a “biological glue” by possessing a high affinity for binding to specific:

Sugar molecules.

Why must plant defensins typically be prepared using cold extraction methods (like raw medicinal seed oils) rather than the hot-water decoction used for cyclotides?

Because they lack the cyclic backbone of cyclotides, making them much more sensitive to heat degradation.

Most medical plant peptides begin as linear, unfolded chains assembled by Transfer RNA (tRNA) at which cellular site?

The ribosome

What specific chemical bonds act as “molecular staples” to lock plant peptides into their bioactive 3D shapes?

Disulfide bridges (cysteine-cysteine bonds)

Cyclotides were first identified in the 1970s as the active agents in what type of traditional medicine?

African labor-inducing teas

What specific phospholipid head group makes up a significant portion of insect and human cell membranes and is the primary target for cyclotide binding?

Phosphatidylethanolamine (PE)

Why must certain lectin-rich foods, such as raw beans, be properly prepared (e.g. heated) before human consumption?

Intact lectins can cause severe GI distress by sticking to the lining of the gut

The primary mode of action for cyclotides defending a plant against pests is binding to phaophatidylethanolamine (PE) headgroups and causing what cellular event?

Severe leakage of cellular contents through oligomeric pores.

While cyclotides are common in the Violaceae family and found in several others, they have notably never been detected in which group of plants?

Monocotyledonous plants (Grasses or Lilies).

Rather than catalyzing chemical reactions like enzymes, how do lectins primarily function in biological systems?

They act as a “biological glue,” sticking tightly to specific oligosaccharides or glycoproteins.

Aside from disrupting membranes, cyclotides can trigger cellular signaling responses without entering the cell by acting as ligands (agonists) for which specific human receptors?

G-protein coupled receptors (GPCRs), such as oxytocin or bradykinin B1 receptors.

How can certain lectins stimulate the human immune system to fight pathogens or tumors?

By binding to specific sugar residues on the surface of human macrophages and T-cells, thereby activating them.

What structural motif allows cyclotides to be exceptionally stable and resist degradation from extreme temperatures and digestive enzymes?

The Cyclic Cystine Knot.

How are “peptides” generally distinguished from “proteins”?

Peptides usually refer to shorter chains of under 100 amino acids.

In addition to physically disrupting cell membranes, some plant defensins prevent insects from digesting plant material by inhibiting which specific enzymes in the insect’s gut?

Alpha-amylases

Certain toxic lectins (like Type II RIPs from castor beans or mistletoe) trigger cell death by physically disabling which cellular machinery?

Ribosomes.

Traditional extracts of Viscum album (European Mistletoe), which are rich in lectins, are typically prepared using cold maceration or cold-pressing for what primary reason?

Lectins are heat-labile, and cold preparation ensures their large, fragile protein structures remain intact and bioactive.

Cyclotides challenge Lipinski’s “Rule of Five” because they remain orally active despite having which characteristic?

They are large molecules (molecular weight greater than 500 Daltons).

What fatty acid, derived from dietary Omega-6s like linoleic acid, serves as the direct precursor in the eicosanoid cascade and is metabolized by COX/LOX enzymes into highly inflammatory prostaglandins and leukotrienes?

Arachidonic acid (ARA)

During biosynthesis, the fatty acid chain is sequentially elongated by the addition of Malonyl-CoA, which loses one carbon as carbon dioxide during condensation, naturally occurring fatty acid carbon backbones are almost always multiples of what number?

2

Why are certain plant-derived fatty acids like linoleic acid (Omega-g) and alpha-linolenic acid (Omega-3) strictly essential in the human diet?

Humans lack the enzymes to insert double bonds past the 9th carbon

During the initial chain elongation step in the biosynthesis of fatty acids and polyketides, a sequential Claisen condenstation occurs between a two-carbon acetyl group and a three-carbon malonyl group. What specific chemical event provides the thermodynamic push that makes this condensation reaction irreversible.

The loss of one carbon from malonyl-CoA as carbon dioxide (decarboxylation)

During the biosynthesis of both fatty acids and polyketides, the growing chain is elongated by sequentially adding two-carbon units derived from which three-carbon precursor?

Malonyl

Aloe vera is well-known for producing the polysaccharide acemannan, but is also produces what polyketide-derived anthraquinone glycoside that is a potent stimulant laxative?

Aloin

Both fatty acids and polyketides are constructed from an assembly line that almost always begins with which two-carbon molecule attached to CoA?

Acetyl

In terms of plant chemistry, how are fixed plant oils (fatty acids/lipids) primarily distinguished from essential oils (terpenes)?

Fixed oils are non-volatile, whereas essential oils are volatile

What is the primary difference in the synthesis of complex polyketides compared to fatty acids?

Polyketide Synthase (PKS) omits reductive steps, leaving reactive oxygen-rich beta-keto groups intact.

Which specific saturated fatty acid (14:0), commonly found in nutmeg and coconut oil, is crucial for cell signaling but can raise LDL cholesterol with excessive intake?

Myristic acid

Omega-3 fatty acids compete with Omega-6 derivatives for COX/LOX enzymes, generally resulting in the production of what?

Less inflammatory or anti-inflammatory mediators.

The core reaction driving the chain elongation of both fatty acids and polyketides, which is made irreversible by decarboxylation (loss of carbon dioxide), is called a:

Claisen condensation

What unusual fatty acid, primarily sourced from castor bean oil, contains a hydroxyl (-OH) group that makes it a potent, direct stimulant of smooth muscle?

Ricinoleic acid

Essential fatty acids (EFAs) are necessary in the human diet because humans cannot insert double bonds past which carbon?

The 9th carbon

While polyketides are heavily involved in plant defense and signaling, what is the primary role of plant fatty acids?

Serving as essential building blocks for cell membranes and concentrated energy storage

Chaulmoogra Oil (Hydnocarpus wightianus) contains rare cyclopentenyl fatty acids and holds a unique place in medical history because it was used for centuries to treat which specific disease?

Leprosy