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Elements of Life

Remember learning the color wheel in art class? Combine blue and yellow, and you can get a shade of green. We say a “shade” of green because what you get depends on how much of each color you put together. Add a generous amount of red, and you might get a shade of brown. But add a tiny bit of red, and you might get a warmer shade of green. 

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Elements of Life

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Remember learning the color wheel in art class? Combine blue and yellow, and you can get a shade of green. We say a “shade” of green because what you get depends on how much of each color you put together. Add a generous amount of red, and you might get a shade of brown. But add a tiny bit of red, and you might get a warmer shade of green.

The vast range of colors that we see around us can be reduced to three primary colors: blue, red, and yellow (note that this is not the case in physics!).

Now think of the different life forms that exist on Earth. From the tiniest bacteria to the massive blue whale, all organisms can be broken down into a few elements that are combined in varying proportions, structures, and through different chemical reactions. So, let's talk about the different elements of life!

  • First, we will discuss the major elements of life.
  • Then, we will look at the 4 fundamental elements of life,
  • After, we will dive into some examples of major elements in life.
  • Lastly, we will talk about essential and trace elements.

What Are The Major Elements Of Life?

All life forms are made up of matter, and all forms of matter are made up of varying combinations of elements. Elements are defined as fundamental units of matter that cannot be broken down or converted into other substances through ordinary chemical reactions. The smallest particle of an element that maintains its chemical properties is called an atom.

At present, there are a total of 118 elements: 92 of these elements occur in nature, whereas the rest are synthesized in laboratories and tend to be unstable (Fig. 1).

Matter refers to any substance that takes up space and has mass. It is made of a combination of elements.

What are the 4 fundamental elements of life in biology?

Out of the 92 naturally occurring elements, only a handful make up all life on Earth.

Four elements are common to all living things: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). These four elements alone make up approximately 96% of all living matter. Sulfur (S), phosphorus (P), calcium (Ca), potassium (K), and a few other elements constitute the other 4% of an organism’s mass. Together, these elements are also sometimes referred to as bulk or major elements of life.

Elements found in living organisms are quite different from those of non-living things. For example, the atmosphere contains a lot of nitrogen and oxygen but very little carbon and hydrogen. On the other hand, the earth’s crust contains oxygen and hydrogen but contains only trace amounts of nitrogen and carbon.

What are examples of major elements in everyday life?

In the following section, we will discuss how these elements combine in various ways to form compounds present in all living things. Specifically, we will discuss how these elements combine to form water and organic compounds.

Water

Recall that all living things are composed of basic units called cells. A cell is primarily made up of water, which accounts for 70% of its mass. Keep in mind that intracellular processes also typically take place in an aqueous environment. This means that all life on Earth largely depends on the unique properties of water.

Water molecules are composed of two hydrogen atoms linked to an oxygen atom via a polar covalent bond. A covalent bond is formed when atoms share electrons in their outermost shell.

In a water molecule, the oxygen atom is highly electronegative, while the hydrogen atoms are less electronegative. This creates an uneven distribution of electrons, where there is a partially positive region on one side and a partially negative region on the other. This makes water a polar molecule.

Because it is a polar molecule, water molecules are able to form hydrogen bonds. Hydrogen bonding gives water molecules important life-sustaining properties including cohesion, moderation of temperature, and the ability to dissolve polar substances such as sodium chloride (also known as table salt).

Intracellular processes are processes that take place within the cell. These are said to take place within an aqueous environment because the cytoplasm (the fluid that fills the cell) is mainly composed of water.

Carbon and biological macromolecules

In addition to water, cells are composed of carbon-based compounds that may contain up to 30 or so carbon atoms.

Carbon has an excellent ability to form large molecules: it has four electrons and four vacancies in its outermost shell, which means it can form up to four covalent bonds with other atoms.

Covalent bonds are chemical bonds that are formed between atoms that are sharing electrons.

Additionally, a carbon atom can attach to other carbon atoms through highly stable covalent carbon-to-carbon bonds that form chains and rings, allowing it to yield large and complex molecules. Such carbon-based compounds are called organic molecules.

Some of these organic molecules are monomers, which are simple subunits that bond together to form polymeric macromolecules. Other organic molecules are energy-rich substances that are broken down and converted into other smaller molecules in intracellular metabolic pathways.

You can consider a polymer to be a train made up of identical railroad cars, with each ‘car’ representing a monomer.

All organic molecules are made from and degrade into similar simple compounds. Both their synthesis and breakdown take place through sequences of chemical reactions that are restricted in scope and adhere to strict constraints. As a result, the compounds in a cell are similar in chemical composition, and the majority of them can be categorized as follows:

Carbohydrates are polymers composed of monosaccharides which are compounds made up of carbon, hydrogen, and oxygen with the general formula (CH2O)n, where n is typically a number from 3 to 8. An example of a monosaccharide is glucose (C6H12O6), an important source of energy for cells.

Lipids are polymers composed of fatty acids and glycerol. Fatty acids are made up of a hydrocarbon (C-H) chain and a carboxyl (-COOH) group. Glycerol is made up of carbon, hydrogen, and oxygen with the formula C3H8O3. An example of a lipid is the phospholipid, which is composed of a phosphate group, a glycerol, and two fatty acid chains (Fig. 2). Phospholipids make up the plasma membrane that encloses all living cells.

Proteins are polymers composed of amino acids. Amino acids are made up of a carboxylic acid group (-COOH), an amino group (-NH2), an organic R group or side chain, and a single carbon atom. Twenty types of amino acids are found in proteins, each with a different R group. These 20 amino acids are found in proteins, whether they are from bacteria, plants, or animals.

Nucleic acids are composed of nucleotides. Nucleotides consist of a nitrogenous base linked to a five-carbon sugar and a phosphate group. DNA and RNA, which contain the genetic information of all living organisms, are nucleic acids.

While there are many compounds found in cells that do not fall into these categories, these four families of organic molecules make up a significant portion of cell mass.

What are other related concepts in relation to elements needed for life?

We have discussed how the four major elements (carbon, hydrogen, oxygen, and nitrogen), along with a handful of other elements (such as sulfur, calcium, and potassium) make up all living organisms.

However, there are some other concepts related to elements that could be worth noting. In this section, we will define essential and trace elements.

What are essential elements?

Out of the 92 naturally occurring elements, around 20-25% are considered essential elements that organisms need to survive and reproduce.

Organisms need similar essential elements, although in varying degrees. For example, humans require around 25 elements, while plants need only 17. Figure 1 below shows a list of essential elements in plants.

Note that these are categorized into macronutrients which are required in large amounts and micronutrients which are required in trace amounts (Fig. 3).

Macronutrients
Micronutrients
Required in large amountsRequired in trace amounts
carbon, phosphorus, nitrogen, hydrogen, potassium, magnesium, oxygen, calcium, sulfurcopper, iron, zinc, boron, manganese, molybdenum, nickel, chlorine

Figure 3. This table shows the essential elements that plants require in order to grow and develop normally.

Without these essential elements, a plant may not be able to complete its life cycle: its seeds may not germinate, or it may be unable to form healthy roots, stems, leaves, or flowers. There are also possibilities that the plant may be unable to produce seeds at all. Worse, the plant itself could die.

What are trace elements?

While organisms require some elements in giant quantities (for instance, we have mentioned earlier that plants require macronutrients like carbon and phosphorus in huge amounts), they require other elements in minute quantities. The latter are called trace elements.

Some trace elements–like iron (Fe)–are required by all living organisms, while other trace elements are needed only by certain organisms.

For instance, vertebrates require iodine (I), an essential component of a hormone produced by the thyroid gland. In humans, 0.15 milligrams (mg) of iodine is required daily for the thyroid to function properly. A person deficient in iodine will suffer from a condition called goiter, wherein the thyroid gland grows to an abnormal size. This is why table salt is typically "iodized", meaning a small amount of iodine is added to it.

Zinc (Zn), copper (Cu), selenium (Se), chromium (Cr), cobalt (Co), iodine (I), manganese (Mn), and molybdenum (Mo) are all essential trace elements in the human body. Despite accounting for only 0.02 percent of total body weight, these components are crucial for certain biological processes, such as active sites of enzymes.

Elements of Life - Key takeaways

  • All life forms are made up of matter, and all forms of matter are made up of varying combinations of elements.
  • Four elements are common to all living things: carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). These four elements alone make up approximately 96% of all living matter.
  • Sulfur (S), phosphorus (P), calcium (Ca), potassium (K), and a few other elements constitute the other 4% of an organism’s mass.
  • In addition to water which constitutes about 70% of a cell's mass, cells are composed of carbon-based compounds that may contain up to 30 or so carbon atoms.
  • These carbon-based compounds include the four biological macromolecules that make up all living things: carbohydrates, lipids, proteins, and nucleic acids.

References

  1. Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. The Chemical Components of a Cell. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26883/
  2. Reece, Jane B., et al. Campbell Biology. Eleventh ed., Pearson Higher Education, 2016.
  3. Zedalis, Julianne, et al. Advanced Placement Biology for AP Courses Textbook. Texas Education Agency.
  4. Provin, Tony L., and Mark L. McFarland. “Essential Nutrients for Plants - How Do Nutrients Affect Plant Growth?” Texas A&M AgriLife Extension Service, 4 Mar. 2019, https://agrilifeextension.tamu.edu/library/gardening/essential-nutrients-for-plants/.

Frequently Asked Questions about Elements of Life

The elements that make up most life forms are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). 

Five elements namely, carbon (C ), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S) make up most life forms. 

Elements of life are the fundamental elements that make up living matter.

In addition to water, living matter are made up of carbon-based molecules. This is because carbon has an excellent ability to form large molecules: it has four electrons and four vacancies in its outermost shell, so it can form four covalent bonds with other atoms. Additionally, a carbon atom can attach to other carbon atoms through highly stable covalent Carbon-to-carbon bonds that form chains and rings which enable it to form large and complex molecules.

Final Elements of Life Quiz

Elements of Life Quiz - Teste dein Wissen

Question

Acids give protons

Show answer

Answer

True

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Question

Bases accept protons

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Answer

True


Show question

Question

Can a solution be an acid and a base?

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Answer

Yes

Show question

Question

What is an amphoteric substance? 

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Answer

A substance that can either be an acid or a base

Show question

Question

What is a conjugate acid?

Show answer

Answer

A base that gains a proton

Show question

Question

What is a conjugate base?

Show answer

Answer

An acid that loses a proton

Show question

Question

What is the conjugate acid of H2O and what is the conjugate base of H2O?

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Answer

Conjugate acid: H3O+

Conjugate base: OH- 

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Question

What products are formed by acid-base reactions?

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Answer

Salt and water

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Question

What happens to strong acids and strong bases in aqueous solutions?

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Answer

Strong acids: completely dissociate in an aqueous solution, forming H+ ions 

Strong bases: completely dissociate in an aqueous solution, forming OH- ions 

Show question

Question

What pH would an acidic substance have?

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Answer

Less than 7

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Question

What is the pH of a basic substance?

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Answer

Greater than 7

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Question

What is the formula to find pH and pOH? 

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Answer

pH + pOH= 14

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Question

What is autoionization?

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Answer

The ability of water to react with itself to produce H+ and OH- ions

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Question

What is a buffer? 

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Answer

A solution that is capable of mitigating pH change after acids or bases are added 

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Question

What are titrations used for? 

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Answer

Determining the concentration of an unknown solution using the concentration of a known solution

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Question

This refers to any substance that takes up space and has mass. 

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Answer

Matter

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Question

This refers to fundamental units of matter that cannot be broken down or converted into other substances through ordinary chemical reactions

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Answer

Element

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Question

The smallest particle of an element that maintains its chemical properties is called a/an ___.

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Answer

atom

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Question

Which of the following are the four major elements that make up all life forms on Earth?

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Answer

carbon, hydrogen, oxygen, nitrogen

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Question

Are the major elements that make up living organisms the same as those found in non-living things? Explain. 

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Answer

Elements found in living organisms are quite different from those of non-living things. For example, the atmosphere contains a lot of nitrogen and oxygen but very little carbon and hydrogen. On the other hand, the earth’s crust contains oxygen and hydrogen but contains only trace amounts of nitrogen and carbon. 

Show question

Question

What are the primary compounds that make up a cell?

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Answer

Water

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Question

Water molecules are composed of ____ linked to an oxygen atom via a polar covalent bond. 

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Answer

two hydrogen atoms

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Question

Why is carbon able to form large molecules essential to life? 

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Answer


Carbon has an excellent ability to form large molecules because it has four electrons and four vacancies in its outermost shell, which means it can form up to four covalent bonds with other atoms. Additionally, a carbon atom can attach to other carbon atoms through highly stable covalent carbon-to-carbon bonds that form chains and rings, allowing it to yield large and complex molecules. 

Show question

Question

What are organic molecules?

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Answer

Organic molecules are carbon-based compounds.

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What elements make up monosaccharides?

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Answer

carbon

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What compounds make up fatty acids?

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Answer

hydrocarbon chain

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Lipids consist of fatty acids and glycerol. What elements make up glycerol?

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Answer

carbon

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What are amino acids composed of?

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Answer

a carboxylic acid group (-COOH), an amino group (-NH2), an organic R group or side chain, and a single carbon atom

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Question

Which of the following can be found in a nucleotide?

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Answer

nitrogenous base

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Question

What are trace elements?

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Answer

Trace elements are essential elements that organisms need in tiny or minute quantities. 

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Question

The smallest units of an element that maintain all of the different properties of that element are called ___.

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Answer

atoms

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Question

Atoms can transfershare, or cause charge differences in electrons to form _____ bonds

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Answer

chemical

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Question

Atoms form chemical bonds because elements are more stable when their valence shell is _____.

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Answer

filled

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Why do atoms with incomplete valence shells participate in chemical bonding?

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Answer

By sharing or transferring valence electrons, atoms with incomplete valence shells can attain a more stable electron configuration

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Question

What is the octet rule?

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Answer

The octet rule states that atoms are typically more stable when they have eight electrons in their valence shell. 

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Question

The process by which two or more atoms bond together to form molecules or bonded atoms dissociate is called a ____.

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Answer

chemical reaction

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A ____  bond is a type of chemical bond that is formed when atoms share electrons in their valence shell. 

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Answer

covalent

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A ___can be used to depict the chemical bond, where a line represents a chemical bond 

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Answer

structural formula

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A double bond is formed between ___.

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two pairs of electrons

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What is electronegativity?

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Answer

Electronegativity is the ability of an atom to attract electrons.

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Question

Which of the following statements is true?

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Answer

The higher its electronegativity, the more strongly an atom pulls shared electrons toward itself. 

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Question

When atoms have the same electronegativity, the electrons are shared ___

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Answer

equally

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Question

When atoms share electrons equally, they form a ___ covalent bond.

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Answer

non-polar 

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The movement of electrons from one element to another is called ___

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Answer

electron transfer

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Question

What causes ionic bonds to form?

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Answer

The attraction between anions and cations lead to the formation of ionic bonds.

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Question

Ionic bonds are chemical bonds formed between ions with ___ charges. 

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Answer

opposite

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Question

What is a hydrogen bond?

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Answer

The attraction between the partial positive charge of the hydrogen and the partial negative charge of the electronegative atoms of the other molecule is called a hydrogen bond.

Show question

Question

How are hydrogen bonds different from ionic and covalent bonds?

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Answer

Hydrogen bonds are different from ionic and covalent bonds: whereas ionic and covalent bonds are intramolecular electrostatic attractions (they hold atoms together within a molecule), hydrogen bonds are intermolecular forces (they occur between molecules). 

Show question

Question

What are van der Waals interactions?

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Answer

Van der Waals interactions are weak intermolecular forces that are based on asymmetrical variations in electron concentrations surrounding an atom 

Show question

Question

What is the smallest particle that makes up an element, that maintains all the different properties of that element?

Show answer

Answer

Atom

Show question

Test your knowledge with multiple choice flashcards

Next

Flashcards in Elements of Life79

Start learning

Acids give protons

True

Bases accept protons

True


Can a solution be an acid and a base?

Yes

What is an amphoteric substance? 

A substance that can either be an acid or a base

What is a conjugate acid?

A base that gains a proton

What is a conjugate base?

An acid that loses a proton

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