Edexcel IGCSE Biology Paper 1

Questions and Answers

What are the characteristics of living things? (Select all that apply)

Excrete (correct)

Sensitivity (correct)

Grow (correct)

Nutrition (correct)

Respire (correct)

Move (correct)

Control (correct)

Describe eukaryotic cells.

Complex large cell; contain nucleus; any mammal/insect cell.

Describe prokaryotic cells.

Small simple cell; no nucleus; floating DNA; Amoeba/Chlorella.

What is the structure of an animal cell?

Multicellular; contain no cell wall; store carbohydrates as glycogen; any mammal/insect. Signup and view all the answers

What is the structure of a plant cell?

Cell wall, vacuole, chloroplasts; store carbohydrates as starch or sucrose; beans/maize. Signup and view all the answers

Describe the structure and feeding method of fungi.

Body called mycelium made up of hyphae; cell walls made of chitin; saprotrophic nutrition; store carbohydrates as glycogen; yeast. Signup and view all the answers

Describe the levels of organization.

Organelle, cell, tissue, organ, organ system. Signup and view all the answers

What is the function of the mitochondria?

Cellular respiration for energy. Signup and view all the answers

What is the function of ribosomes?

Protein synthesis. Signup and view all the answers

What is the function of chloroplasts?

Contains chlorophyll which absorbs light energy for photosynthesis. Signup and view all the answers

What is the function of vacuoles?

Stores water, salts, proteins, and carbohydrates and provides structure. Signup and view all the answers

Define pathogen.

Disease causing organism. Signup and view all the answers

Describe viruses.

Small cells, can only reproduce in living cells, no cellular structure, protein coat and contain DNA or RNA; HIV. Signup and view all the answers

Describe bacteria.

Single-celled, no nucleus, contain circular chromosomes of DNA, contain plasmids; Lactobacillus. Signup and view all the answers

Define cell differentiation.

The process by which cells become specialized in structure and function. Signup and view all the answers

What are the structure and elements in carbohydrates?

Carbon, Hydrogen, Oxygen; starch/glycogen. Signup and view all the answers

What are the structure and elements in lipids?

Carbon, Hydrogen, Oxygen; fatty acids and glycerol. Signup and view all the answers

What are the structure and elements in proteins?

Carbon, Hydrogen, Oxygen, Nitrogen; amino acids. Signup and view all the answers

How to test for starch?

Addition of iodine (orange) reacts with starch to produce brown/blue color. Signup and view all the answers

How to test for lipids?

Add drops of Sudan III, shake; red lipids settle on top. Signup and view all the answers

How to test for proteins?

Biuret test; add biuret solution and shake; blue -> pink if present. Signup and view all the answers

How to make a food sample?

Break food in pestle and mortar; stir with distilled water; filter solution to remove solids. Signup and view all the answers

How to test for glucose?

Benedict solution in a hot water bath - blue -> turns green-yellow-brick red. Signup and view all the answers

Describe the process of photosynthesis.

Light energy is absorbed by chlorophyll in chloroplasts, used to convert carbon dioxide and water into sugar (glucose); oxygen is released. Signup and view all the answers

What is the word and chemical equation for photosynthesis?

Carbon dioxide + water > glucose + oxygen; $6CO_2 + 6H_2O = C_6H_{12}O_6 + 6O_2$ Signup and view all the answers

What are the adaptations of a leaf?

Large surface area; upper epidermis transparent allows light in; most chloroplasts found in palisade cells near top; waxy cuticle prevents water loss. Signup and view all the answers

What do plants need mineral ions for?

Growth. Signup and view all the answers

What is a plant's use for nitrates and deficiency symptoms?

Used for supply of nitrogen to make amino acids and protein; stunted growth; leaves go yellow. Signup and view all the answers

What is a plant's use for phosphates and deficiency symptoms?

Used for making DNA and cell membranes; poor root growth; leaves turn purple. Signup and view all the answers

What is a plant's use for potassium and deficiency symptoms?

Help enzymes for photosynthesis and respiration; poor flower/fruit growth; discolored leaves. Signup and view all the answers

What is a plant's use for magnesium and deficiency symptoms?

Used for making chlorophyll; yellow leaves. Signup and view all the answers

What is the body's use for carbohydrates and found in?

Energy; pasta, rice, sugar. Signup and view all the answers

What is the body's use for lipids and found in?

Energy, energy storage, insulation; found in fats and oils. Signup and view all the answers

Study Notes

Characteristics of Living Things

Essential characteristics: movement, respiration, sensitivity, growth, excretion, nutrition, and control.

Eukaryotic Cells

Complex and larger cell type.
Contains a nucleus.
Examples include any mammalian or insect cell.

Prokaryotic Cells

Simple and smaller cell type.
Lacks a nucleus; contains floating DNA.
Examples include Amoeba and Chlorella.

Animal Cells

Multicellular organisms; no cell wall.
Store carbohydrates as glycogen.
Found in any mammal or insect.

Plant Cells

Have a cell wall, vacuole, and chloroplasts.
Store carbohydrates as starch or sucrose.
Common examples: beans and maize.

Fungi Structure and Nutrition

Body composed of mycelium formed from hyphae (thread-like structures).
Walls made from chitin.
Nutrition obtained through saprotrophic means, releasing enzymes to break down food.
Store carbohydrates as glycogen, with yeast as a typical example.

Levels of Organization

Hierarchical structure includes: organelle, cell, tissue, organ, organ system.

Mitochondria Function

Responsible for cellular respiration, providing energy.

Ribosomes Function

Sites for protein synthesis within the cell.

Chloroplast Function

Contains chlorophyll, essential for absorbing light energy in photosynthesis.

Vacuole Function

Stores water, salts, proteins, and carbohydrates; also provides structural support.

Pathogen Definition

An organism that causes disease.

Viruses

Small, non-cellular entities that reproduce within living cells.
Composed of a protein coat and contain either DNA or RNA.
An example includes HIV.

Bacteria

Single-celled organisms without a nucleus.
Contain circular chromosomes of DNA and plasmids (additional small DNA fragments).
Example: Lactobacillus.

Cell Differentiation

The process in which cells become specialized, adapting specific structures and functions.

Carbohydrates Composition

Composed of carbon, hydrogen, and oxygen.
Forms include starch and glycogen.

Lipids Composition

Composed of carbon, hydrogen, and oxygen.
Includes fatty acids and glycerol.

Proteins Composition

Composed of carbon, hydrogen, oxygen, and nitrogen.
Basic building blocks are amino acids.

Starch Test

Iodine solution (orange) reacts with starch, turning brown/blue.

Lipid Test

Sudan III added, shaken; red lipids layer floats on top.

Protein Test

Biuret test: adding biuret solution changes color from blue to pink if proteins are present.

Food Sample Preparation

Crush food in a pestle and mortar, mix with distilled water, and filter to remove solids.

Glucose Test

Benedict's solution heated; blue changes to green-yellow-brick red if glucose is present.

Photosynthesis Process

Light energy absorbed by chlorophyll, converting carbon dioxide and water into glucose, releasing oxygen.

Photosynthesis Equation

Word equation: Carbon dioxide + water → glucose + oxygen.
Chemical equation: 6CO2 + 6H2O = C6H12O6 + 6O2.

Leaf Adaptations

Large surface area for light absorption.
Transparent upper epidermis allows light penetration.
Palisade cells near the top contain most chloroplasts.
Waxy cuticle prevents water loss.

Plant Mineral Ions

Mineral ions are crucial for plant growth and healthy development.

Nitrates in Plants

Supply nitrogen for amino acid and protein production, thus promoting growth.
Deficiency symptoms: stunted growth and yellow leaves.

Phosphates in Plants

Important for DNA, cell membranes, respiration, and growth.
Deficiency symptoms include poor root growth and purple leaves.

Potassium's Role in Plants

Vital for enzyme function in photosynthesis and respiration.
Deficiency symptoms: poor flower/fruit growth and discolored leaves.

Magnesium in Plants

Essential for chlorophyll production.
Deficiency results in yellowing leaves.

Carbohydrates in the Body

Primary energy source.
Found in foods like pasta, rice, and sugar.

Lipids in the Body

Serve various roles including energy, storage, and insulation.

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