Biology IGCSE Past Papers Mistakes

Questions and Answers

Name 2 statements that are correct about yeast.

Can be used in the production of beer. 2. Cell wall is made of chitin.

What is meant by a group of organs?

Made of tissues that perform a specific function.

Explain how changes in respiration stop gazelles from running at a top speed for a long time.

As the gazelle is running at a top speed, its body can't supply enough oxygen to the muscles for a long time, so it has to start respiring anaerobically. 2. This is because it has less oxygen for aerobic respiration. 3. The glucose is then partially broken down, producing lactic acid.

Use your knowledge of natural selection to explain how a striped coat that reduces the number of flies feeding on zebra blood may have evolved.

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How would the layer of cells behind a lion's retina that reflects light help a lion see in low light intensities?

<p>As light passes through the retina twice.</p> Signup and view all the answers

Suggest an adaptation in the structure of an animal's eye that helps it see in low light intensities.

<p>Size of pupil expands.</p> Signup and view all the answers

Why does the saliva released into a lion's mouth not contain amylase when it eats meat?

<ol> <li>This is because the meat in the lion's mouth is protein. 2. Amylase doesn't break down protein.</li> </ol> Signup and view all the answers

Describe the events that take place from when pollen lands on the stigma of a flower to when a seed is formed.

<ol> <li>Pollen grain lands on a stigma of a flower. 2. A pollen tube grows out of the pollen grain into the style to the ovule. 3. Male gamete nucleus moves down the tube. 4. Joins female gamete in the ovule. 5. The 2 nuclei fuse to form a zygote, which then divides by mitosis into an embryo.</li> </ol> Signup and view all the answers

Method that can be used to estimate the population of fire ants in an area.

<ol> <li>Quadrat sampling can be used. 2. They can be thrown at random. 3. Repeated several times. 4. Then count the number of fire ants inside the quadrant.</li> </ol> Signup and view all the answers

Suggest how this diuretic causes more urine to be produced.

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Describe how a student could measure the heart rate.

<ol> <li>Place fingers on wrist/neck/artery. 2. Count pulse for a minute.</li> </ol> Signup and view all the answers

Study Notes

Yeast Characteristics

Yeast is utilized in beer production.
The cell wall of yeast is composed of chitin.

Group of Organs

A group of organs consists of tissues that perform a specific function together.

Gazelles and Respiration

Gazelles cannot sustain top speeds due to insufficient oxygen for muscles.
Anaerobic respiration occurs because of reduced aerobic respiration.
Partial breakdown of glucose leads to lactic acid production.

Natural Selection and Zebras

Not provided; consider factors like survival advantages and predator-prey interactions for a striped coat evolution.

Lion's Eye Adaptation

A reflective layer behind the retina allows light to be used effectively, enhancing visibility in low light.

Animal Eye Adaptation

Larger pupil size facilitates better light intake in dim conditions.

Lion's Saliva Composition

Lion saliva lacks amylase because the diet mainly consists of protein.
Amylase is an enzyme that breaks down carbohydrates, not proteins.

Pollen to Seed Formation Process

Pollen grain lands on stigma of a flower.
A pollen tube extends from the grain into the style toward the ovule.
Male gamete nucleus descends through the tube.
Male and female gametes unite in the ovule, forming a zygote.
The zygote divides via mitosis to produce an embryo.

Estimating Fire Ant Population

Utilize quadrats to sample an area.
Randomly throw quadrats multiple times.
Count the number of fire ants within each quadrant to estimate population size.

Diuretics and Urine Production

Not provided; typically, diuretics increase urine output by inhibiting water reabsorption in kidneys.

Measuring Heart Rate

Place fingers on the wrist, neck, or artery to locate pulse.
Count the number of beats for a full minute to determine heart rate.

Description

This quiz focuses on mistakes and frequently asked questions from past IGCSE Biology papers. Students will review key concepts, such as yeast functions and organ definitions, to reinforce their understanding. Ideal for exam preparation and self-assessment.