IGCSE Biology Paper 2 Review

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Questions and Answers

A person quickly pulls their hand away after touching a hot object. Which characteristic of living organisms does this demonstrate?

  • Excretion
  • Reproduction
  • Sensitivity (correct)
  • Growth

Which type of organism is commonly used in genetic modification due to the presence of plasmids?

  • Arachnids
  • Myriapods
  • Ferns
  • Bacteria (correct)

Consider the following cell structures: cytoplasm, cell membrane, cell wall, and chloroplast. How many of these are found in all living organisms?

  • 1
  • 2 (correct)
  • 3
  • 4

A student draws a red blood cell with a diameter of 20 mm. If the actual diameter of the cell is 0.008 mm, what is the magnification of the drawing?

<p>×2500 (B)</p> Signup and view all the answers

Plant cells are immersed in distilled water, a low concentration sucrose solution, and a high concentration sucrose solution. The low concentration solution has a higher water potential than the cytoplasm of the plant cells; the high concentration sucrose solution has a lower water potential than the cytoplasm. What describes the state of the cells?

<p>Turgid, turgid, plasmolysed (D)</p> Signup and view all the answers

Which cellular process directly requires energy produced during respiration?

<p>Active transport (D)</p> Signup and view all the answers

The sticky end of a DNA plasmid has been cut by a restriction enzyme and the unpaired bases are labeled. What is the correct sequence of the missing bases?

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

A food substance yields a blue-black color change after undergoing a specific test. Which solution was used for this test?

<p>Iodine solution (D)</p> Signup and view all the answers

A student investigates the breakdown of fats in milk using lipase in four test tubes with different combinations of milk, bile, and boiled or unboiled lipase. In which test tube will the contents become acidic most quickly?

<p>Milk, bile, no lipase, lipase (B)</p> Signup and view all the answers

An experiment measures the rate of photosynthesis in an aquatic plant by measuring bubble release. As light intensity increases, the rate of bubble release increases then becomes constant. Which statement describes why bubble rate plateaus at high light intensities?

<p>Carbon dioxide concentration becomes a limiting factor. (D)</p> Signup and view all the answers

In which labeled areas of a leaf section cross section does photosynthesis primarily take place?

<p>2 and 3 (B)</p> Signup and view all the answers

Which labeled part of the alimentary canal and associated organs shown stores bile?

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

Which two statements correctly describe the role of villi in humans?

<p>Villi increase the efficiency of absorption of nutrients. Villi provide a large surface area. (A)</p> Signup and view all the answers

Diagrams show carbohydrate molecules as they pass through the alimentary canal. Which row correctly represents the molecules?

<p>Before: complex, Mouth: less complex, Small Intestine: simple (A)</p> Signup and view all the answers

Which row correctly associates the functions and locations of lipase, maltase, and trypsin?

<p>Lipase: small intestine, Maltase: small intestine, Trypsin: alkaline conditions (C)</p> Signup and view all the answers

Which dietary component is vital for preventing constipation?

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

Under which weather conditions is the transpiration rate of a well-watered plant expected to be highest?

<p>Hot, dry, windy day (B)</p> Signup and view all the answers

During photosynthesis in a flowering plant, which statement accurately describes the source and sink relationship for sucrose?

<p>The leaves are a source of sucrose and the fruits are a sink. (C)</p> Signup and view all the answers

What is one advantage of a double circulatory system?

<p>Deoxygenated and oxygenated blood are separated to allow a high rate of oxygen supply to the tissues. (A)</p> Signup and view all the answers

What happens in coronary heart disease?

<p>Part A is blocked (C)</p> Signup and view all the answers

Flashcards

Sensitivity in Biology

The capacity of living organisms to respond to stimuli.

Organisms Used in Genetic Modification

Organisms like bacteria, which contain plasmids, can be used. Plasmids enable genetic modification.

Active transport

Energy is needed to move molecules against a concentration gradient, from a low to high concentration.

Iodine Test

Change to blue-black color indicates the presence of starch. Iodine solution is used as an indicator for this.

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Lipase and Bile

Lipase breaks down fats, producing fatty acids which are acidic. Bile emulsifies fats, increasing the surface area for lipase to act on.

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Limiting Factor

Carbon dioxide concentration becomes a limiting factor. The rate of photosynthesis no longer increases with light intensity.

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Villi Function

Villi increase the surface area for nutrient absorption in the small intestine.

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Fibre Role

Fibre adds bulk to the diet, which aids bowel movement and prevents constipation.

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High Transpiration

Transpiration rate is highest when it's hot, dry, and windy because these conditions increase evaporation.

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Photosynthesis site

The leaves are the primary site of photosynthesis in a plant, acting as a source of sucrose.

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Double Circulation

A double circulatory system allows for efficient oxygen supply to tissues by keeping oxygenated and deoxygenated blood separate.

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Cholera and Diarrhoea

Chloride ions into the small intestine lowers the water potential, causing water to move into the intestine, leading to diarrhea.

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Antibody Action

Antibodies have a specific shape that matches the antigen they act against, like a lock and key.

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Remove Oxygen Debt

Aerobic respiration of lactic acid in the liver. Oxygen is used to convert lactic acid back to glucose.

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Kidney Reabsorption

In kidney nephrons, glucose is entirely reabsorbed back into the blood to maintain blood sugar levels.

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Body Cooling

Vasodilation increases blood flow, and the pupil size decreases. Lens shape becomes thin.

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Antibiotics Action

Antibiotics are effective against bacteria, interfering with their essential functions.

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Pollen Tube

Pollen tube is a hollow tube that develops from a pollen grain when deposited on the stigma of a flower.

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Stem cells

Unspecialised cells capable of differentiating into various cell types.

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Natural selection

Natural selection causes species to develop advantageous traits from their environment.

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Study Notes

  • The IGCSE Biology Paper 2 is a multiple-choice exam that assesses extended-level content.
  • The exam duration is 45 minutes.
  • The paper consists of 40 questions.
  • Each correct answer is worth one mark, totaling 40 marks.
  • A soft pencil, eraser, and calculator may be used.

Characteristics of Living Organisms

  • Sensitivity is exemplified by a person rapidly moving their hand away from a hot object.

Genetic Modification

  • Bacteria are used in genetic modification because they contain plasmids.

Cell Structures

  • Cytoplasm and cell membrane are cell structures found in all living organisms.

Magnification

  • Calculating magnification: drawing diameter / actual diameter = 20 mm / 0.008 mm = ×2500.

Plant Cells and Water Potential

  • In distilled water, plant cells are turgid.
  • In a low concentration sucrose solution, plant cells are plasmolysed.
  • In a high concentration sucrose solution, plant cells are flaccid.
  • Low concentration sucrose solution has higher water potential than plant cell cytoplasm.
  • High concentration sucrose solution has a lower water potential than plant cell cytoplasm.

Energy and Respiration

  • Active transport requires energy from respiration.

DNA and Restriction Enzymes

  • Given the sticky end of DNA with unpaired bases, the complementary sequence is CAGTG.

Food Tests

  • Iodine solution tests for starch, indicated by a color change to blue-black.

Enzymes and Digestion

  • Lipase acts in acidic conditions, maltase acts in the stomach, and trypsin is secreted by the pancreas.

Fats and Lipase

  • In the test tube containing milk, bile, and lipase the contents tested acidic the quickest.

Photosynthesis

  • As light intensity increases, the rate of bubble release increases, and then the light intensity becomes a limiting factor.

Plant Anatomy and Photosynthesis

  • Photosynthesis takes place in parts 2 and 3 of a flowering plant leaf.

Alimentary Canal

  • The gall bladder stores bile, which is labelled part D.

Villi

  • Villi increase the efficiency of nutrient absorption and Villi provide a large surface area.

Carbohydrates and Digestion

  • Carbohydrate molecules broken down correctly as they breakdown in the mouth and small intestine.

Healthy Diet

  • Fiber helps prevent constipation.

Transpiration

  • The transpiration rate is highest on a hot, dry, windy day for a well-watered plant.

Sucrose in Plants

  • The leaves are a source of sucrose, and the fruits are a sink during photosynthesis.

Double Circulatory System

  • A double circulatory system allows for a high rate of oxygen supply to the tissues by separating deoxygenated and oxygenated blood.

Heart Disease

  • Part D of the diagram shows the external structure of the human heart, which if blocked, can cause coronary heart disease.

Cholera

  • Cholera toxins cause diarrhoea by secreting chloride ions into the small intestine, lowering the water potential.

Immunity

  • Babies develop passive immunity from the antibodies they receive in breast milk.

Gas Exchange

  • The diaphragm contracts to cause breathing in, and cilia carry mucus to the throat.

Oxygen Debt

  • Aerobic respiration of lactic acid in the liver removes oxygen debt.

Kidney Function

  • Glucose is completely reabsorbed into the blood from the kidney nephrons.

Eyes and Light

  • In a brightly lit room, a person reading a text message would have small pupils and a fat lens shape.

Thermoregulation

  • Vasodilation increases blood flow to the skin surface capillaries to maintain a constant internal temperature on a hot day.

Blood Glucose

  • Increased release of insulin leads to a decrease in blood glucose concentration.

Antibiotics

  • Antibiotics do not affect bacteria but kill bacteria.

Flower Anatomy

  • The pollen tube is the name of part X of a flower.

Sperm Abnormalities

  • Person P cannot digest the jelly coat of the egg cell whereas Person Q cannot move to the oviduct, thus both have low fertility.

Stem Cells

  • The word unspecialised describes stem cells.

Menstrual Cycle graph

  • The line that represents progesterone is B on the Menstrual cycle graph.

Genetic Disorders

  • The pedigree diagram that proves the genetic disorder is a dominant allele is B with three generations.

Meiosis

  • Meiosis does not produce genetically identical cells and is in repair of damaged tissues.

Natural Selection

  • Leafy sea dragons that looked like seaweed were better adapted to their environment, and Leafy sea dragons that survived passed on the allele for their appearance to their offspring

Biological Systems

  • The Sun is the main source of energy input to biological systems.

Soil

  • Denitrifying bacteria and plants remove nitrate ions from the soil.

Reasons for endangerment

  • Habitat destruction and pollution are two reasons for organisms becoming endangered.

Genetic Modification in Agriculture

  • Inserting genes into crop plants can improve the nutritional qualities of the plant.

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