Cell Structure and Photosynthesis Quiz

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Questions and Answers

Which component is essential for all cells and serves as the boundary between the cell interior and the external environment?

Cytoplasm

Ribosomes

DNA

Cell membrane (correct)

What is a defining feature of prokaryotic cells?

Presence of a nucleus

Multicellularity

Single loop of DNA in the cytoplasm (correct)

Complex membrane-bound organelles

What is the primary role of ribosomes within a cell?

To store genetic information

To assist in photosynthesis

To regulate cell division

To synthesize proteins (correct)

Which of the following options represents the correct equation for photosynthesis?

Carbon dioxide + Water ------> Glucose + Oxygen Signup and view all the answers

How does temperature affect the photosynthesis process in plants?

Higher temperatures provide more kinetic energy for reactants Signup and view all the answers

What is found in plant cells but not in animal cells?

Chloroplasts Signup and view all the answers

What structure surrounds all prokaryotic cells and is typically made of peptidoglycan?

Cell wall Signup and view all the answers

What role does glucose play in the photosynthesis process?

It is utilized for energy and building substances in the plant Signup and view all the answers

What happens to enzymes that control photosynthesis when the temperature increases too much?

They denature and lose their function. Signup and view all the answers

How does light intensity affect the rate of photosynthesis?

Photosynthesis increases with light intensity until another factor limits it. Signup and view all the answers

What role do chloroplasts play in photosynthesis?

They absorb light energy for photosynthesis. Signup and view all the answers

Which of the following factors does NOT affect the number of chloroplasts in a plant?

Excessive water Signup and view all the answers

What is one of the uses of glucose in plants?

It is used to produce cellulose for strengthening cell walls. Signup and view all the answers

What indicates the presence of starch in a leaf after the iodine test?

The leaf turns blue or black. Signup and view all the answers

What causes enzymes to denature?

Changes in temperature and pH levels. Signup and view all the answers

Why do plants require carbon dioxide for photosynthesis?

To facilitate the chemical reaction of photosynthesis. Signup and view all the answers

What is the lock and key model an analogy for in enzyme function?

The way substrates and enzymes fit together Signup and view all the answers

What occurs when an enzyme exceeds its optimum temperature?

The enzyme starts to denature Signup and view all the answers

Which type of enzyme is responsible for breaking down carbohydrates?

Amylase Signup and view all the answers

What effect does a low pH have on enzyme activity?

It can lead to denaturation of the enzyme Signup and view all the answers

What happens to enzymes at lower temperatures?

They experience reduced kinetic energy Signup and view all the answers

Where does protein digestion primarily occur?

Stomach and duodenum Signup and view all the answers

What is a characteristic of lipases?

They break down lipids into glycerol and fatty acids Signup and view all the answers

What happens to the active site of an enzyme when it denatures?

It changes shape and cannot bind to the substrate Signup and view all the answers

Study Notes

Cell Structure

All cells contain:
- Cell membrane
- Cytoplasm
- DNA
- Ribosomes
Eukaryotic cells have a nucleus which contains their genetic material.
- Examples include plant and animal cells.
Prokaryotic cells do not have their genetic material enclosed within a nucleus.
- The genetic material is found within the cytoplasm as a single loop of DNA.
- Smaller circular pieces of DNA may also be present.
- Bacterial cells are a type of prokaryotic cell.
- The cell membranes of all prokaryotic cells are surrounded by a cell wall, usually made from peptidoglycan.

Photosynthesis

Photosynthesis is an endothermic reaction where light energy is transferred to the chloroplast.
Equation: Carbon dioxide + Water -----> Glucose + Oxygen
Carbon dioxide diffuses into the leaf through the stomata
Water is absorbed into the leaf and transported via the xylem to the leaves
Glucose is used to produce substances needed by the plant and for respiration
Oxygen diffuses out of the leaf through the stomata and is used for respiration

Factors affecting the rate of photosynthesis

Temperature:
- The temperature affects the rate of photosynthesis because it impacts the kinetic energy of particles, influencing the rate that carbon dioxide and water are transported throughout the plant.
- Lower temperatures decrease kinetic energy, leading to fewer collisions between molecules, slowing the reaction rate.
- Increasing temperatures increase kinetic energy resulting in more collisions between reactants and enzymes, producing more product.
- However, exceeding an optimal temperature can denature enzymes, eventually decreasing the rate of photosynthesis.
Light intensity:
- The intensity of light available to the plant dictates the amount of energy available for photosynthesis.
- Greater light intensity leads to a higher rate of photosynthesis until other factors become limiting.
Carbon dioxide:
- Carbon dioxide is a reactant in photosynthesis, with greater CO2 concentration leading to faster reaction rates.
- This trend continues until other limiting factors prevent further increases in the rate of photosynthesis.
Chloroplast:
- Chloroplasts contain chlorophyll, the pigment that absorbs light energy used in photosynthesis.
- Increased chloroplast abundance promotes faster photosynthesis.
- Factors that can impact chloroplast number include disease, loss of leaves, and nutrient deficiency.

Uses of glucose in plants

Respiration
Cellulose production to strengthen cell walls
Amino acids for protein synthesis (combining with nitrate ions)
Fats and oils for storage
Insoluble starch for storage in stems, leaves, and roots

Testing for starch in plants

Purpose: To show the effect of light on photosynthesis
Steps:
1. Boil the leaf in water: This breaks down the cell walls.
2. Place the leaf in ethanol and heat it to remove chlorophyll: The ethanol removes the chlorophyll.
3. Rinse the leaf in water to soften it.
4. Add iodine solution to the leaf: Iodine solution will turn blue/black in the presence of starch.
5. Observe the color changes for the presence of starch.

Enzymes

Biological catalysts that speed up chemical reactions
Made from protein, where amino acids are bonded together to maintain the enzyme's shape.
Specificity: Determined by the complementary shape of the active site on the enzyme and its substrate.
Lock and Key Model:
- Enzymes and substrates move randomly within solutions.
- When an enzyme and its complementary substrate collide, with the substrate fitting into the active site: an enzyme-substrate complex forms, and the reaction occurs.
- The product(s) of the reaction are released from the active site, leaving the enzyme unchanged to catalyze further reactions.

Effects of temperature and pH on enzyme activity:

Temperature:
- Enzymes function fastest at their optimum temperature (37°C for humans).
- Increasing temperature from 0°C to the optimum increases enzyme activity.
- Lower temperatures do not denature enzymes, but decrease the rate molecules collide, slowing down reactions.
- Heating beyond the optimum breaks bonds, causing the enzyme to denature and lose its shape, reducing its effectiveness and eventually stopping activity.
pH:
- Extremes in pH can disrupt the bonds holding the amino acid chain together, altering the shape of the active site and preventing the substrate from binding.
- This reduces enzyme activity.
- Moving too far from the optimum pH causes denaturation and stops enzyme activity.

Enzymes and Digestion

Three main types of digestive enzymes:
- Carbohydrases: Break down carbohydrates into simple sugars.
  - Amylase is a carbohydrase that breaks down starches into maltose.
  - Made in the pancreas, small intestine, and salivary glands.
- Proteases: Break down proteins into amino acids.
  - Protein digestion occurs in the duodenum of the small intestine and the stomach.
  - Produced in the pancreas and small intestine.
- Lipases: Break down lipids (fats) into glycerol and fatty acids.
  - Made in the pancreas and secreted into the duodenum.

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Description

Test your knowledge on cell structure and the process of photosynthesis. This quiz covers the key components of eukaryotic and prokaryotic cells, as well as the critical steps involved in photosynthesis and its equation. Perfect for biology students looking to reinforce their learning!