Biology: Carbohydrates and Lipids
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Questions and Answers

Which of the following is a type of carbohydrate used as an energy store in animal cells?

  • Glycogen (correct)
  • Glucose
  • Cellulose
  • Starch

Glucose is a carbohydrate that is insoluble in water.

False (B)

What is the chemical formula for glucose?

C6H12O6

The solution that turns blue-black when mixed with starch is called __________ solution.

<p>iodine</p> Signup and view all the answers

What percentage of the human body mass is made up of carbohydrates?

<p>1% (B)</p> Signup and view all the answers

Match the following carbohydrates with their respective functions:

<p>Glucose = Energy transport Starch = Energy storage in plants Glycogen = Energy storage in animals Cellulose = Structural component in plant cell walls</p> Signup and view all the answers

Cells require glycogen to produce energy.

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

Reducing sugars, such as __________, can turn Benedict’s solution orange-red when heated.

<p>glucose</p> Signup and view all the answers

What is the primary use of cellulose in plants?

<p>Making plant cell walls (D)</p> Signup and view all the answers

Fats are lipids that are liquid at room temperature.

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

What are the smaller molecules that make up fat molecules?

<p>Glycerol and fatty acids</p> Signup and view all the answers

Proteins are made of long chains of ______ linked together.

<p>amino acids</p> Signup and view all the answers

Match the enzyme with its substrate:

<p>Amylase = Starch Protease = Protein Catalase = Hydrogen peroxide Maltase = Maltose</p> Signup and view all the answers

Which component is necessary for the enzyme-catalyzed reaction to occur?

<p>Substrate (C)</p> Signup and view all the answers

All enzymes can act on any type of substrate.

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

What is the function of hemoglobin in mammals?

<p>Transporting oxygen in blood</p> Signup and view all the answers

The two strands of a DNA molecule are coiled around one another, forming a ______ shape.

<p>double helix</p> Signup and view all the answers

Match the enzyme to its action:

<p>Amylase = Breaks down starch Protease = Breaks down proteins Lipase = Breaks down lipids Sucrase = Breaks down sucrose</p> Signup and view all the answers

What is an emulsion?

<p>A liquid containing two substances that do not fully mix (C)</p> Signup and view all the answers

The Biuret reagent turns blue in the presence of proteins.

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

What are the four bases of DNA?

<p>A, T, C, G</p> Signup and view all the answers

Enzymes lower the ______ energy required for a chemical reaction to occur.

<p>activation</p> Signup and view all the answers

Which part of the leaf contains most of the chloroplasts for photosynthesis?

<p>Palisade mesophyll (A)</p> Signup and view all the answers

Guard cells are found in the upper epidermis and do not contain chloroplasts.

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

What is the main function of the spongy mesophyll in a leaf?

<p>Gas exchange</p> Signup and view all the answers

The __________ is a thin layer of wax that covers the upper surface of a leaf.

<p>cuticle</p> Signup and view all the answers

Match the leaf tissues to their functions:

<p>Palisade mesophyll = Photosynthesis Spongy mesophyll = Gas exchange Guard cells = Control stoma opening Upper epidermis = Protection and secretion</p> Signup and view all the answers

Which factor can limit the rate of photosynthesis when in short supply?

<p>All of the above (D)</p> Signup and view all the answers

Destarching involves keeping a plant in the dark to prevent it from using starch stores.

<p>True (A)</p> Signup and view all the answers

What happens to the rate of photosynthesis if the temperature is too high?

<p>Enzymes denature and the rate drops.</p> Signup and view all the answers

The rate of photosynthesis increases with elevated __________ until a certain concentration is reached.

<p>carbon dioxide</p> Signup and view all the answers

In which of the following conditions would a plant likely close its stomata?

<p>On a hot, sunny day (D)</p> Signup and view all the answers

All cells in the epidermis of a leaf contain chloroplasts.

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

What are the primary raw materials required for photosynthesis?

<p>Carbon dioxide and water</p> Signup and view all the answers

The layer of cells that secretes a waxy substance forming the __________ is the upper epidermis.

<p>cuticle</p> Signup and view all the answers

What is a limiting factor in photosynthesis?

<p>A factor in short supply that limits activity (B)</p> Signup and view all the answers

What is formed when an enzyme binds to its substrate?

<p>Enzyme-substrate complex (C)</p> Signup and view all the answers

The optimum temperature for most enzymes is 60°C.

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

What is denaturation in the context of enzymes?

<p>Denaturation is when an enzyme is damaged and can no longer catalyze reactions.</p> Signup and view all the answers

Photosynthesis is the process by which plants synthesize carbohydrates from raw materials using energy from __________.

<p>light</p> Signup and view all the answers

Which of the following is the primary pigment involved in photosynthesis?

<p>Chlorophyll (C)</p> Signup and view all the answers

Bacteria thriving in hot springs have an optimum temperature of 37°C.

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

What substance do plants primarily store glucose as?

<p>Starch</p> Signup and view all the answers

The process of converting sucrose back into glucose occurs when sucrose arrives at its __________.

<p>destination</p> Signup and view all the answers

What is the role of nectar in flowers?

<p>To attract pollinators (B)</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Photosynthesis = The process of making carbohydrates using light Chlorophyll = The pigment that absorbs sunlight Sucrose = A transportable sugar made from glucose and fructose Denaturation = When an enzyme loses its function due to damage</p> Signup and view all the answers

Most plants can only make glucose in parts that contain chlorophyll.

<p>True (A)</p> Signup and view all the answers

What do plants need to synthesize proteins from amino acids?

<p>Nitrogen ions</p> Signup and view all the answers

The collection of xylem tubes and phloem vessels in a leaf is known as a __________ bundle.

<p>vascular</p> Signup and view all the answers

Why is the large surface area of leaves advantageous for plants?

<p>Increases the diffusion of carbon dioxide (B)</p> Signup and view all the answers

What color do plant leaves appear when they lack sufficient magnesium and nitrogen?

<p>Yellow</p> Signup and view all the answers

Flashcards

Carbohydrates

Organic compounds containing carbon, hydrogen, and oxygen, including sugars, starch, and cellulose.

Sugars

Simple carbohydrates with small molecules, soluble in water, and taste sweet.

Glucose

A type of sugar used by cells to release energy during respiration. Chemical formula: C₆H₁₂O₆

Glycogen

A storage form of glucose in animal cells.

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Starch

A storage form of glucose in plant cells.

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Iodine solution

Used to test for starch; turns blue-black when mixed with starch.

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Benedict's solution

A chemical test for reducing sugars; turns orange-red when heated with reducing sugars.

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Reducing sugars

Sugars that react with Benedict's solution, turning it orange-red when heated.

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Cellulose

A carbohydrate made of many glucose molecules linked in a chain, forming straight lines, used in plant cell walls.

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Lipids

Substances containing carbon, hydrogen, and oxygen; insoluble in water, used as energy stores

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Fats

Solid lipids at room temperature

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Oils

Liquid lipids at room temperature

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Emulsion

A liquid containing two substances that do not mix.

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Protein

A substance made of chains of amino acids, critical for many functions (e.g., enzymes, antibodies)

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Amino acids

Small molecules containing carbon, hydrogen, oxygen, and nitrogen; building blocks of proteins.

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Enzyme

Proteins that speed up metabolic reactions, acting as biological catalysts.

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Catalyst

A substance that increases the rate of a chemical reaction without being consumed.

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Substrate

The substance an enzyme acts upon.

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Active site

The specific region of an enzyme that a substrate binds to.

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Product

The substance that results from an enzyme-catalyzed reaction.

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Complementary

Having a perfect mirror-image shape, used for enzyme-substrate binding.

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Enzyme-substrate complex

The temporary structure formed when an enzyme binds to its substrate.

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Optimum Temperature

The temperature at which an enzyme works fastest, achieving its highest activity.

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Optimum pH

The specific pH value at which an enzyme exhibits its maximum activity.

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Denaturation

The process where an enzyme loses its shape and function due to extreme changes in temperature or pH.

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How does temperature affect enzyme activity?

Higher temperatures increase enzyme activity until the optimum temperature is reached. Beyond that, denaturation occurs due to extreme heat.

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How does pH affect enzyme activity?

Each enzyme has an optimum pH. Deviation from this pH can cause denaturation and decrease enzyme activity.

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Photosynthesis

The process plants use to convert light energy into chemical energy stored in sugars, using carbon dioxide and water as ingredients.

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Chlorophyll

The green pigment found in plants that absorbs light energy for photosynthesis.

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Photosynthesis Equation

CO2 + H2O + light energy → C6H12O6 + O2

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How do plants use carbohydrates?

Plants use carbohydrates for energy, storage, transport, building cell walls, attracting pollinators, and making other essential substances like chlorophyll.

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Nectar

A sweet liquid produced by flowers to attract pollinators.

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How do plants make amino acids?

Plants use glucose from photosynthesis and nitrogen ions absorbed from the soil to synthesize amino acids, which are the building blocks of proteins.

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Leaf Epidermis

The outer protective layer of a leaf, made of tightly packed cells, preventing water loss. It does not contain chloroplasts.

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Cuticle

A thin, waxy layer secreted by the upper epidermis of a leaf, making it waterproof and reducing water loss.

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Palisade Mesophyll

The layer of cells directly below the upper epidermis, containing abundant chloroplasts, where most photosynthesis occurs.

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Spongy Mesophyll

The layer of cells below the palisade mesophyll, containing fewer chloroplasts, with air spaces for efficient gas exchange.

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Stomata

Openings on the leaf surface, mainly on the lower epidermis, controlled by guard cells for gas exchange.

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Guard Cells

Specialized cells surrounding stomata, containing chloroplasts, which control the opening and closing of stomata.

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Chloroplasts

Organelles within plant cells, responsible for photosynthesis, containing chlorophyll.

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What is destarching? Why is it done?

Destarching is the process of leaving a plant in the dark for an extended period to deplete its starch stores. This is done to ensure the plant starts with minimal starch before an experiment, allowing researchers to isolate effects on photosynthesis.

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What is a control in an experiment?

A control is a standard, unchanged sample used for comparison in an experiment. It helps determine the effect of changing a specific variable.

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Limiting Factor

A resource that restricts an activity's progress, such as the rate of photosynthesis. It determines the maximum rate possible.

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How does light intensity affect photosynthesis?

Light intensity directly influences the rate of photosynthesis. In darkness, photosynthesis stops. As light intensity increases, the rate of photosynthesis increases until it reaches a maximum.

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How does carbon dioxide affect photosynthesis?

Carbon dioxide is a vital raw material for photosynthesis. As the concentration of carbon dioxide increases, the rate of photosynthesis also increases until it reaches a maximum.

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How does temperature affect photosynthesis?

Temperature affects the rate of photosynthesis by influencing enzyme activity. Warm temperatures increase the rate, but excessively high temperatures can denature enzymes, causing a sharp decrease.

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Why might photosynthesis slow down on a hot sunny day?

On a hot sunny day, the stomata might close to prevent excessive water loss, limiting carbon dioxide intake and slowing down photosynthesis.

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What are arbitrary units used for?

Arbitrary units are used on graphs to represent quantitative differences between values, instead of using complex real units like seconds or centimeters.

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Study Notes

Carbohydrates

  • Carbohydrates are substances like sugars, starch, and cellulose, containing carbon, hydrogen, and oxygen.
  • Sugars are simple carbohydrates with small molecules; they dissolve in water and taste sweet.
  • Glucose is a sugar used in respiration for energy release.
  • Glycogen is an animal energy storage carbohydrate.
  • Starch is a plant energy storage carbohydrate.
  • Iodine solution turns blue-black with starch.
  • Benedict's solution turns orange-red when heated with reducing sugars (e.g., glucose).

Fats and Oils (Lipids)

  • Fats (solid at room temp) and oils (liquid at room temp) are lipids.
  • Lipids contain carbon, hydrogen, and oxygen; they are insoluble in water but dissolve in ethanol.
  • Lipids are energy stores.
  • Fats are composed of glycerol and fatty acids.
  • Fats are important for cell membranes.
  • Fat tissue beneath the skin insulates and stores energy.
  • Ethanol emulsion test: Add ethanol to food; if fats are present, a milky emulsion forms when mixed with water.

Proteins

  • Proteins are made of linked amino acids.
  • Each protein has a unique amino acid sequence.
  • Proteins may contain sulfur.
  • Amino acids contain carbon, hydrogen, oxygen, and nitrogen.
  • Antibodies are proteins that fight pathogens.
  • Keratin is a protein in hair and fingernails.
  • Biuret reagent turns purple with amino acids or proteins.
  • Enzymes are proteins that catalyze metabolic reactions.
  • Hemoglobin carries oxygen in blood.

DNA Structure

  • DNA is a molecule carrying genetic instructions for protein synthesis.
  • DNA is found in every cell's nucleus (except red blood cells).
  • DNA is made of nucleotides.
  • DNA forms a double helix.
  • The four DNA bases are A, C, G, and T.
  • Complementary base pairing (A with T, C with G) occurs in DNA.

Enzymes

  • Enzymes are biological catalysts.
  • Enzymes are proteins that speed up metabolic reactions.
  • Amylase breaks down starch to maltose.
  • Protease breaks down proteins to amino acids.
  • Catalase breaks down hydrogen peroxide to water and oxygen.
  • Enzymes have an active site where substrates bind.
  • The substrate fits the active site, like a lock and key.
  • The enzyme-substrate complex forms temporarily.

Factors Affecting Enzyme Activity

  • Enzymes work best at their optimum temperature and pH.
  • High temperatures or extreme pH denature enzymes, disrupting their structure and activity.
  • Temperature increases enzyme activity until the optimum is reached.
  • pH affects enzyme activity. Enzymes have an optimal pH range.

Plant Nutrition

  • Plants make carbohydrates via photosynthesis.
  • Photosynthesis uses light energy to produce carbohydrates from water and carbon dioxide.
  • Chlorophyll absorbs light.
  • Plants store excess glucose as starch for later use.
  • Sucrose is the transport form of sugar in plants.
  • Cellulose forms plant cell walls.
  • Plants need nitrogen for amino acid synthesis.
  • Plants need magnesium for chlorophyll production.

Leaf Structure

  • Leaves have a large surface area for maximizing sunlight and CO2 intake.
  • Leaves have a thin structure to allow diffusion of gases.
  • Leaves have vascular bundles (veins) for transport.
  • Monocots have parallel veins; dicots have networked veins.
  • Leaf tissues include epidermis (upper and lower), cuticle, palisade mesophyll (photosynthesis), spongy mesophyll (gas exchange), and stomata (gas exchange).
  • Guard cells control stomata opening/closing.

Factors Affecting Photosynthesis

  • Photosynthesis rate is affected by light intensity, CO₂ concentration, temperature, and chlorophyll amount.
  • Light, CO₂, and temperature can be limiting factors, slowing down photosynthesis when scarce. Hot temperatures can denature enzymes crucial to photosynthesis.
  • Stomata closing can prevent water loss but also reduces CO₂ intake, limiting photosynthesis.

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Description

This quiz covers essential concepts of carbohydrates and lipids, including their structures, functions, and tests. Understand the differences between simple and complex carbohydrates, as well as the role of fats and oils in energy storage and insulation. Test your knowledge on these crucial biomolecules in living organisms.

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