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9th grade How small molecules join into big ones worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

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How small molecules join into big ones

Grade 9 Science Worksheet - Building Confidence

NameDate

Circle the best answer.

  1. Read this first

    Use this

    Building-block chain, not to scale. 2 beads in a row: glycerol, fatty-acid; each neighbor pair is joined by a covalent bond. Bead A is a glycerol bead; bead B is a fatty-acid bead.

  2. Esme studies a chain. Glycerol bead A and fatty-acid bead B are joined by a covalent bond. What is that bond called?

    • No bond: the beads just sit together
    • A glycosidic bond
    • An ester bond
    • A peptide bond

  3. Building-block chain, not to scale. Jun watches a model of 3 amino-acid beads joining into one chain. A water bead floats off at each join. What reaction is this?

    • Dehydration synthesis: the beads join and water is used
    • Dehydration synthesis: the beads join and water is released
    • Hydrolysis: the beads join and water is used
    • Neither: the beads join with no water involved

  4. Building-block chain, not to scale. 3 water beads arrive, one at each bond. Kira watches a model of a 4-bead sugar chain being split apart. A water bead joins in at each bond. What reaction is this?

    • Hydrolysis: the chain splits and water is used
    • Hydrolysis: the chain splits and water is released
    • Neither: the chain splits with no water involved
    • Dehydration synthesis: the chain splits and water is released

  5. Building-block chain, not to scale. Luz watches a model of a glycerol bead and a fatty-acid bead linking up. One water bead floats away. What reaction is this?

    • Hydrolysis: the two beads link and one water is used
    • Dehydration synthesis: the two beads link and one water is released
    • Dehydration synthesis: the two beads link and one water is used
    • Neither: the two beads link with no water involved

  6. The released waters are not drawn. Milo builds a chain of 4 amino-acid beads. Each join released one water. Count the joins in the drawing. How many waters were released altogether?

    • 4 waters
    • 1 water
    • 5 waters
    • 3 waters

  7. Use this

    Building-block chain, not to scale. 6 glucose beads in a row, each neighbor pair joined by a glycosidic bond. The released waters are not drawn.

  8. Noah builds a chain of 6 glucose beads. Each join released one water. Count the joins in the drawing. How many waters were released altogether?

    • 1 water
    • 4 waters
    • 5 waters
    • 6 waters

  9. The released waters are not drawn. Pia builds a short chain of 5 amino-acid beads. Each join released one water. Count the joins in the drawing. How many waters were released altogether?

    • 6 waters
    • 3 waters
    • 4 waters
    • 5 waters

  10. not to scale. Ren reads that a long chain of beads is called a polymer. What does the word polymer mean?

    • A chain of monomers joined by covalent bonds
    • A single small building block, such as one amino acid
    • A covalent bond that links two neighboring beads
    • A water molecule that is released at a join

  11. Tala sees the term dehydration synthesis on a card. Which meaning fits?

    • Break pieces apart by adding water
    • Put pieces together by adding water
    • Join pieces with no water involved
    • Put pieces together while losing water

  12. Zee sees the term hydrolysis on a card. Which meaning fits?

    • Break a chain apart with no water involved
    • Break a chain apart by adding water
    • Put pieces together while losing water
    • Break a chain apart by releasing water
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9th grade How small molecules join into big ones worksheet – printable
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About this worksheet

How small molecules join into big ones. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can tell dehydration synthesis (monomers join, a covalent bond forms, one water is released per bond) from hydrolysis (a water is added across a bond and the polymer splits). Digestion is hydrolysis.
  • I can name the bond: peptide (amino acids), glycosidic (sugars), ester (glycerol and fatty acids).
  • I can count: a chain of n monomers has n − 1 bonds, so building it releases n − 1 waters and splitting it completely uses n − 1 waters. I can work backward from the waters to the monomers.
  • I can say why a polymer has less mass than its monomers added up (the released waters left), and why the pieces from hydrolysis have more mass than the chain (the added water).
  • I can say that digested food is not turned into new atoms: its atoms are rebuilt into new molecules, for example sugar's carbon, hydrogen and oxygen combine with nitrogen to build amino acids.

Standard: HS-LS1-6

Words to know

monomer: A small building block, such as one amino acid or one sugar

polymer: A large molecule made of many monomers joined together

covalent bond: A bond where atoms share electrons

dehydration synthesis: Join pieces while losing water: one water per bond

hydrolysis: Split a chain by adding a water across each bond

peptide bond: The bond between two amino acids

glycosidic bond: The bond between two sugars

ester bond: The bond between glycerol and a fatty acid

Common mistakes

Your child mixed up joining and splitting. Joining pieces releases a water; splitting a chain uses a water.

Your child counted one water for every piece. A chain of 5 pieces has only 4 joins. Draw 5 dots in a row and count the gaps between them.

Your child thought the pieces just stick or come unstuck. Real molecules join by covalent bonds, and each join releases a water.

What to say

Ask: which one puts together while losing water?

Ask: what leaves when two pieces join?

Questions parents ask

What is the most common mistake with how small molecules join into big ones?

Your child mixed up joining and splitting. Joining pieces releases a water; splitting a chain uses a water.

How can I help my child with how small molecules join into big ones?

Ask: which one puts together while losing water?

Are these 9th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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