Biochemistry of Bioelements and Water
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Questions and Answers

Which elements are considered primary bioelements in living organisms?

  • Sulfur, Phosphorus, Nitrogen
  • Iron, Zinc, Fluorine
  • Carbon, Hydrogen, Oxygen, Nitrogen
  • Carbon, Hydrogen, Oxygen, Phosphorus, Nitrogen, Sulfur (correct)

What percentage of living matter do trace elements (oligoelements) account for?

  • 0.1% (correct)
  • 0.01%
  • 5%
  • 1%

Which property is NOT associated with the main bioelements suited for life?

  • Low atomic mass
  • Ability to form covalent bonds
  • High abundance
  • High solvency in organic solvents (correct)

Which organic biomolecules are primarily composed of carbon, hydrogen, and oxygen?

<p>Both B and C (D)</p> Signup and view all the answers

What is the primary function of oligoelements such as iron and zinc in living organisms?

<p>Regulating biological functions (D)</p> Signup and view all the answers

What is the structural composition of water?

<p>Two atoms of hydrogen and one atom of oxygen (C)</p> Signup and view all the answers

At what temperature does water begin to exhibit a crystalline structure due to decreased density?

<p>4°C (B)</p> Signup and view all the answers

Which property of water is attributed to its high molecular cohesion?

<p>High surface tension (A)</p> Signup and view all the answers

What is a biological function of dissolved salts in living organisms?

<p>Regulating pH levels (B)</p> Signup and view all the answers

What role do precipitated salts play in biological systems?

<p>They contribute to structural formation (B)</p> Signup and view all the answers

What role does water play in temperature regulation in living organisms?

<p>It absorbs and releases heat to help regulate body temperature. (B)</p> Signup and view all the answers

Which example best illustrates the function of water in metabolic reactions?

<p>Participating in photosynthesis in plants. (D)</p> Signup and view all the answers

In the context of substance transportation, what is a primary feature of water?

<p>It has a high capacity for dissolving various substances. (D)</p> Signup and view all the answers

What is an example of water's protective function in living beings?

<p>Cerebrospinal fluid cushioning the brain. (D)</p> Signup and view all the answers

What process is water NOT primarily involved in?

<p>Neural impulse transmission (A)</p> Signup and view all the answers

What is the primary function of osmosis in cells?

<p>To allow solvent to pass through a semipermeable membrane. (B)</p> Signup and view all the answers

In a hypertonic medium, what initial effect occurs to a red blood cell?

<p>The cell shrinks as it loses water. (B)</p> Signup and view all the answers

What happens to a red blood cell placed in a hypotonic medium?

<p>It will swell and potentially burst. (A)</p> Signup and view all the answers

Which statement best describes an isotonic medium?

<p>Equal solute concentration inside and outside the cell. (C)</p> Signup and view all the answers

How does water movement occur during osmosis?

<p>From higher water concentration to lower water concentration. (D)</p> Signup and view all the answers

What occurs with water movement across a membrane in an isotonic medium?

<p>Water moves in both directions equally. (B)</p> Signup and view all the answers

In an isotonic medium, what drives the movement of water across the cell membrane?

<p>Concentration gradients (B)</p> Signup and view all the answers

Which statement best describes the dynamic in an isotonic medium?

<p>Water movement is consistently equal in both directions. (B)</p> Signup and view all the answers

How would water movement change if the medium became hypotonic?

<p>Water would move inwards, potentially causing cell swelling. (A)</p> Signup and view all the answers

What distinguishes an isotonic medium from a hypertonic medium regarding water movement?

<p>Water moves towards areas of higher solute concentration in hypertonic media. (D)</p> Signup and view all the answers

What occurs in a hypertonic medium regarding the cell's water content?

<p>Water leaves the cell, causing dehydration. (B)</p> Signup and view all the answers

What happens to plant cells in a hypotonic medium?

<p>They fill vacuoles with water, increasing turgor pressure. (C)</p> Signup and view all the answers

What is the primary characteristic of an isotonic medium?

<p>Water moves out of the cell without affecting its size. (A)</p> Signup and view all the answers

Why do plant cells not burst in a hypotonic medium unlike red blood cells?

<p>Plant cells have a rigid cell wall that prevents bursting. (B)</p> Signup and view all the answers

What occurs to the vacuoles of a plant cell when placed in a hypotonic medium?

<p>The vacuoles fill with water, increasing pressure. (C)</p> Signup and view all the answers

What is one of the primary roles of bicarbonate in biological fluids?

<p>To regulate the pH levels (D)</p> Signup and view all the answers

How does bicarbonate help prevent drastic changes in pH?

<p>By absorbing protons when acid levels rise (A)</p> Signup and view all the answers

What happens to bicarbonate when there is an excess of base in biological fluids?

<p>It acts as a proton donor, decreasing acidity (A)</p> Signup and view all the answers

Which of the following statements correctly describes the dissociation of bicarbonate?

<p>$HCO_3^−$ can accept protons to form $CO_3^{2-}$ (D)</p> Signup and view all the answers

Which other compounds, besides bicarbonate, are crucial for maintaining pH in biological fluids?

<p>Phosphate and proteins (D)</p> Signup and view all the answers

What happens to the density of water when it freezes?

<p>It decreases, causing it to float on liquid water. (B)</p> Signup and view all the answers

How does water's high specific heat capacity affect living organisms?

<p>It helps in maintaining stable temperatures. (B)</p> Signup and view all the answers

What property of water allows it to dissolve many substances effectively?

<p>Its polarity as an excellent solvent. (B)</p> Signup and view all the answers

Why is cohesion important for water's role in biological systems?

<p>It contributes to the transport of nutrients and fluids. (B)</p> Signup and view all the answers

What allows some organisms to move across the surface of water?

<p>The high surface tension of water. (D)</p> Signup and view all the answers

How does capillary action primarily benefit plants?

<p>By allowing water to rise from roots to leaves. (D)</p> Signup and view all the answers

What is the primary biological function of water's high heat of vaporization?

<p>To facilitate temperature regulation through cooling. (B)</p> Signup and view all the answers

What combined effect of cohesion and adhesion in water allows nutrient transport in organisms?

<p>Capillary action and strong hydrogen bonding. (D)</p> Signup and view all the answers

Flashcards

Bioelements

Chemical elements found in living organisms.

Primary elements

Bioelements making up 99% of living matter.

Oligoelements

Trace elements needed by living organisms in small amounts (< 0.1%).

Carbon (C), Hydrogen(H), Oxygen (O), Nitrogen(N), Phosphorus (P), Sulfur (S)

The main building blocks of organic biomolecules.

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Organic biomolecules

Molecules primarily containing carbon, hydrogen, and oxygen.

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Water's structure

Two hydrogen atoms and one oxygen atom form a bent, tetrahedral shape, with each water molecule forming four hydrogen bonds with its neighbors.

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Water's density anomaly

Unlike most substances, water becomes less dense when it freezes into ice, due to its hydrogen bonding network expanding, causing ice to float.

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Water's high heat capacity

Water absorbs a lot of heat energy before its temperature rises, making it a good temperature regulator for living organisms and the environment.

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Dissolved salts: Regulators

Minerals dissolved in solutions like blood control osmotic pressure, pH levels, and various important processes in the body.

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Precipitated salts: Structures

Minerals in solid form provide structural support for bones, shells, teeth, and other hard structures in living organisms.

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What is a buffer system?

A buffer system helps maintain a stable pH in a living organism by neutralizing changes. It prevents drastic shifts in acidity or alkalinity.

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Bicarbonate buffer system

A common buffer system in the body that regulates pH in intracellular fluids. It involves the reversible reaction between bicarbonate ions, carbonic acid, carbon dioxide, and water.

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Water as a solvent

Water's ability to dissolve a wide range of substances makes it crucial for transporting nutrients, minerals, oxygen, and waste products throughout the body.

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Water in temperature regulation

Water helps regulate body temperature through sweating, which removes heat as water evaporates. This cooling mechanism is crucial for maintaining a stable internal temperature.

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Water's role in metabolism

Water participates in many metabolic reactions, such as photosynthesis in plants, breaking down large molecules (hydrolysis), and cellular respiration (energy production).

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Osmosis

The movement of water across a semipermeable membrane from a region of high water concentration to a region of lower water concentration.

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Hypertonic solution

A solution with a higher concentration of solutes than the cell's internal environment.

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Hypotonic solution

A solution with a lower concentration of solutes than the cell's internal environment.

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Isotonic solution

A solution with the same concentration of solutes as the cell's internal environment.

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What happens to an animal cell in a hypertonic solution?

The cell loses water and shrinks due to osmosis, as the water moves out of the cell to the area of higher solute concentration outside the cell.

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Isotonic Medium

A solution that has the same concentration of solutes as the cell's cytoplasm, resulting in no net movement of water. The cell maintains its stable size and shape.

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Hypertonic Medium

A solution with a higher concentration of solutes than the cell's cytoplasm. Water moves out of the cell, causing it to shrink and potentially dehydrate.

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Hypotonic Medium

A solution with a lower concentration of solutes than the cell's cytoplasm. Water moves into the cell, causing it to swell and increase in size.

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What happens to a plant cell in a hypotonic medium?

The cell absorbs water, increasing the size of its vacuoles and creating turgor pressure. The cell expands but typically doesn't burst as in a red blood cell.

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What happens to a plant cell in a hypertonic medium?

Water leaves the cell, causing the cytoplasm membrane to shrink and the cell to dehydrate. The cell loses its firmness and wilts.

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What happens to water in an isotonic medium?

In an isotonic medium, water moves across the membrane in both directions at the same rate, resulting in no net change in the volume of either side of the membrane.

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Example of an isotonic medium

Blood plasma is an example of an isotonic medium. Red blood cells are able to maintain their normal shape in blood plasma because the concentration of solutes is equal inside and outside the cells.

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Isotonic vs. Hypotonic

In a hypotonic medium, the concentration of solutes is lower outside the cell than inside, causing water to move into the cell and potentially cause it to swell. In an isotonic medium, the concentration of solutes is equal inside and outside the cell, so there is no net movement of water.

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Isotonic vs. Hypertonic

In a hypertonic medium, the concentration of solutes is higher outside the cell than inside, causing water to move out of the cell and potentially cause it to shrink. In an isotonic medium, the concentration of solutes is equal inside and outside the cell, so there is no net movement of water.

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Water's High Specific Heat

Water requires a large amount of energy to change its temperature, allowing for temperature regulation in organisms.

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Water's Excellent Solvent

Water's polarity allows it to dissolve many substances, facilitating their transport in living organisms.

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Water's Cohesion and Adhesion

Water molecules stick together (cohesion) and to other substances (adhesion), allowing for fluid transport.

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Water's High Surface Tension

The strong cohesion between water molecules produces a high surface tension, allowing some objects to float.

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Capillary Action

Water's adhesion and cohesion allow it to move upwards in narrow tubes, transporting water in plants.

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Why is water density important?

Water's density anomaly ensures ice floats, insulating aquatic life during freezing temperatures.

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How does water regulate temperature?

Water's high specific heat capacity allows it to absorb a lot of heat before changing temperature, maintaining stable temperatures.

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Water's pH Regulatory Role

Water's ability to dissociate into ions (H+ and OH-) makes it a key pH regulator in biological systems. This is crucial for maintaining the stability of cellular processes, enzyme function, and overall organismal health.

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How does bicarbonate act as a buffer?

Bicarbonate ($HCO_3^−$) acts as a buffer system by using the following reversible reaction: $HCO_3^- ightleftharpoons H^+ + CO_3^{2-}$. When excess acid ($H^+$) is present, bicarbonate ions absorb the protons, shifting the equilibrium to the left. Conversely, when too much base is present, the reaction shifts to the right, releasing protons and preventing a basic pH.

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Why is pH regulation important for biological fluids?

Maintaining a stable pH is essential for biological fluids because it affects the activity of enzymes, the structure of proteins, and the overall function of cells. Fluctuations in pH can disrupt these processes, leading to cell damage and even death.

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What are other buffer systems besides bicarbonate?

Besides bicarbonate, phosphate and proteins also play important roles in regulating the pH of biological fluids. Phosphate acts as a buffer in intracellular fluids, while proteins can act as both acids and bases, depending on the pH of the solution. These multiple buffer systems ensure a robust and stable pH environment.

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