Biology past paper 1

What kingdom does Euglena belong to, and why?

• Protoctists. It is a microscopic, single-celled organism with a nucleus (eukaryotic) that shares both plant-like and animal-like features.

What is the function of the mitochondrion

It is the site of aerobic respiration where energy (ATP) is released.

Which organelle contains genetic material (chromosomes/DNA)?

The nucleus. It controls all the activities of the cell.

What is the role of the flagellum (Structure R)?

• It is a tail-like structure used for movement/locomotion to propel the organism through water.

Name two structures found in plant cells but not in animal cells.

Chloroplasts and a cellulose cell wall.

What is P

Pellicle, A flexible, protective outer layer that replaces a rigid cell wall

What is Q

Cell membrane ,the inner boundary layer controlling what enters and exits

What is R

Flagellum, The long, tail-like structure used for swimming and movement

What is S

Chloroplast , The site of photosynthesis, containing stacks where light is trapped

What is T

Nucleus The control center containing chromosomes/DNA

What is U

Mitochondrion (The site of aerobic respiration where energy is released)

What does Benedict's solution test for, and what must you do to make it react?

• It tests for glucose (reducing sugars). It must be heated in a hot water bath to work.

What do the different colors of a Benedict's test mean?

• Blue: No glucose Green: Trace/Low glucose Yellow/Orange: Moderate glucose Brick-red: High glucose

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Why do athletes need glucose during a long-distance race?

• Glucose is a substrate for aerobic respiration, which releases energy (ATP) required for muscle contractions.

What is the word equation for anaerobic respiration in humans?

Glucose to Lactic acid + a small amount of energy

State the balanced chemical equation for aerobic respiration.

C6H12O6 + 6O2 to 6CO2 + 6H2O

Why are drinks without glucose better for individuals with diabetes?

Because diabetics cannot effectively regulate their blood sugar (due to a lack of insulin). Glucose-free drinks prevent dangerous blood sugar spikes.

What causes Type 1 diabetes vs Type 2 diabetes

Type 1 where The immune system destroys insulin-producing cells (not lifestyle-related).

Type 2 is where The body cells become resistant to insulin (strongly linked to obesity and diet).

What energy conversion happens during photosynthesis?

Light energy is converted into chemical energy (stored in glucose)

What does "destarching" a plant mean, and how is it done?

• It means removing all stored starch from the leaves. It is done by placing the plant in the dark for 24 to 48 hours.

Why must you destarch a plant before starting a photosynthesis experiment?

To ensure that any starch detected at the end of the experiment was only made during the experiment itself

What reagent is used to test for starch, and what is its positive color change?

• Iodine solution. It changes from orange-brown to blue-black if starch is present.

Why must you boil a leaf in ethanol before adding iodine solution to test for starch?

To remove the green chlorophyll, which decolors the leaf so you can clearly see the blue-black color change.

Give the functions of 2 named mineral ions that a plant needs

Nitrate ions used to make amino acids and proteins. Magnesium ions used to make chlorophyll

In a photosynthesis experiment, what is the role of potassium hydroxide (or sodium hydroxide)?

It absorbs carbon dioxide from the air inside an enclosed container.

What happens to a plant if it suffers from a nitrate deficiency, and why?

It will have stunted growth and older leaves will turn yellow, because it cannot synthesize the proteins needed for growth.

What visual symptom shows a plant has a magnesium deficiency, and why?

• The leaves turn yellow (chlorosis) because the plant cannot produce enough green chlorophyll pigments.

What is active transport

Active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration.

Why do root hair cells require active transport to absorb mineral ions?

Because mineral concentration is usually lower in the soil than inside the plant cell vacuole, meaning they must move against a concentration gradient.

What two things are absolutely required for active transport to happen?

Carrier proteins embedded in the cell membrane and energy released from respiration.

Name two substances carried in the phloem.

Sucrose and amino acids.

plants convert glucose into what

Plants convert glucose into sucrose specifically for transport.

What is the main difference between what the xylem and phloem transport?

Xylem transports water and mineral ions upwards. Phloem transports sucrose and amino acids up and down the plant.

What is the term used for the movement of food substances through the phloem?

Translocation (requires energy from companion cells).

Why do root hair cells in waterlogged soil struggle to perform active transport to absorb mineral ions?

it forces out all the air, leaving no oxygen. Without oxygen, the cells cannot perform aerobic respiration to release the energy (ATP) needed to pump those minerals in.

Why does a chemical insecticide cause a pest population to explode later on

The chemical kills the natural predators (like ladybugs) as well as the pests and A few pests survive because they have a natural genetic resistance to the chemical