Skip to main content

Which of the following is LEAST suited for long-distance phloem transport of photo-assimilated carbon in plants?

Question: Which of the following is LEAST suited for long-distance phloem transport of photoassimilated carbon in plants?

  1. Reducing sugars
  2. Mannitol
  3. Galactosyl-sucrose oligosaccharides
  4. Non-reducing sugars
Answer: 1. Reducing sugar

  • Facts about the Phloem transportation:

Explanation:

  1. Reducing agent: A reducing agent, also known as a reductant, is a substance that donates electrons to another substance in a chemical reaction, thus reducing the oxidation state of that substance. During this process, the reducing agent itself becomes oxidized, losing electrons.
  2. Reducing sugar: A reducing sugar is one that contains a free aldehyde (-CHO) or ketone (-C=O) group, which enables it to act as a reducing agent.
Examples:

  • Monosaccharides: Glucose, Fructose, Galactose
  • Disaccharides: Maltose, Lactose
3. Non-reducing sugar: A non-reducing sugar does not have a free aldehyde or ketone group because it is involved in a glycosidic bond, which prevents it from reducing other compounds.
Examples:
  • Disaccharides: Sucrose
  • Polysaccharides: starch, cellulose, glycogen.
The chemical composition of the substances transported in the phloem: 
Translocated solutes encompass both organic and inorganic compounds. Phloem sap delivers the majority of the inorganic and organic substances essential for plant growth. The main organic solutes include carbohydrates, amino acids, organic acids, hormones, RNAs, and certain secondary metabolites that play a role in defense and protection.
The carbohydrates that are translocated are primarily non-reducing sugars and sugar alcohols, such as sorbitol and mannitol. The most common translocated sugar is sucrose, a disaccharide comprised of one glucose molecule and one fructose molecule.
Some plant families, in addition to sucrose, also translocate oligosaccharides from the raffinose family. Members of this family include raffinose (a trisaccharide), stachyose (a tetrasaccharide), and verbascose (a pentasaccharide). All of these are nonreducing sugars.
Non-reducing sugars are the primary compounds transported in phloem because they are less reactive than reducing sugars.
Reducing sugars, like glucose, are highly reactive. While animals can manage to transport glucose in their blood due to its relatively low concentration, glucose levels cannot be tolerated in phloem, where sugar concentrations are significantly higher.

Comments

Post a Comment

Popular posts from this blog

The problems of life affect the sperm of a young man, due to which the rate of birth of female child from his sperm is higher.

Article: The problems of life affect the sperm of a young man, due to which the rate of birth of female child from his sperm is higher.    This statement touches on a complex and sensitive topic, so let’s break it down carefully and scientifically: Does life stress affect a man's sperm? Yes, to some extent. Chronic stress, poor lifestyle , environmental exposure, and mental health challenges can impact sperm quality — including count, motility (movement), morphology (shape), and DNA integrity. Studies have shown: High cortisol (stress hormone) levels may interfere with testosterone production. Stress can reduce overall sperm count and quality . DNA fragmentation in sperm can increase, affecting fertility and embryo health.  Does stress influence the sex of the child (female vs male)? This is more controversial and less proven , but some studies suggest: Sperm carry either an X (female) or Y (male) chromosome. The “Y” (male) sperm are typically faster but...
Post a Comment
Read more

Differences Between RPM and RCF in Centrifugation

    Differences Between RPM and RCF in Centrifugation In centrifuge operation, it is crucial to differentiate between two distinct units of measurement: Relative Centrifugal Force (RCF) and Revolutions Per Minute (RPM). These units are fundamentally different and confusing them—though not uncommon—can compromise the integrity of an experiment. This discussion will explore RCF and RPM in greater detail and examine their relationship. **Revolutions Per Minute (RPM) Revolutions Per Minute (RPM) refers to the measurement of the rotational speed of a centrifuge rotor, indicating the number of complete rotations it performs in one minute. This metric quantifies the rotor's spinning velocity. Each centrifuge has a specific speed range that varies by model. For instance, a low-speed centrifuge may operate at a minimum of 300 RPM, while a high-speed centrifuge can reach speeds of up to 15,000 RPM. Additionally, ultracentrifuges, the most powerful type, can exceed 150,000 RPM. **Relativ...
Post a Comment
Read more

The Marginal value theorem

  The correct answer is: Option 4: P = Optimum patch residence time ; Q = Time taken to travel between patches Explanation: The Marginal Value Theorem (MVT) is an important concept in behavioral ecology , especially used to describe foraging behavior — how animals decide when to leave a resource patch (like a flower, tree, or field) and move to a new one. Let’s go step by step 👇 🧠 Basic Idea When an animal forages, it gains food (energy) from a “patch.” At first, food is abundant — energy gain is high . As time goes on, food becomes harder to find — rate of gain decreases . So, the animal faces a decision: “Should I keep searching here or move to another patch?” ⚖️ The Principle (Charnov, 1976) The Marginal Value Theorem states: A forager should leave the current patch when the marginal rate of resource gain (the slope of the gain curve at that moment) drops to equal the average rate of gain from the environment (including travel time).   According...
Post a Comment
Read more