BIOLOGY IGCSE EDEXCEL: USES OF BIOLOGICAL RESOURCES

What are glasshouses used for in crop production?

Glasshouses provide an enclosed environment where farmers can control climate factors to increase crop yields.

What are the main conditions that can be manipulated in a glasshouse?

Artificial heating, artificial lighting, increased carbon dioxide content, and regular watering.

What is the purpose of polythene tunnels in agriculture?

Polythene tunnels protect crops from weather effects and pests while slightly increasing temperature.

What is a limiting factor in photosynthesis?

A limiting factor is the resource that is in the shortest supply, restricting the rate of photosynthesis.

What are the three main limiting factors of photosynthesis?

Temperature, light intensity, and carbon dioxide concentration.

How does temperature affect the rate of photosynthesis?

As temperature increases, the rate of photosynthesis increases until enzymes denature at high temperatures.

What happens to the rate of photosynthesis as light intensity increases?

The rate of photosynthesis increases until another limiting factor prevents further increases.

What role does carbon dioxide concentration play in photosynthesis?

Higher carbon dioxide concentration increases the rate of photosynthesis until another factor becomes limiting.

What is the role of fertilizers in crop production?

Fertilizers replace essential mineral ions in the soil, promoting larger and healthier crop growth.

Name two types of fertilizers.

Organic fertilizers (e.g., farmyard manure) and chemical fertilizers.

What mineral ion is needed for chlorophyll production?

Magnesium ions.

What are the signs of magnesium deficiency in plants?

Yellowing of leaves.

What mineral ion is essential for amino acid production?

Nitrate ions.

What are the signs of nitrate deficiency in plants?

Weak growth and yellowing of leaves.

What is the function of phosphate ions in plants?

Phosphate ions are needed for ATP, DNA, and RNA production.

What are the signs of phosphate deficiency in plants?

Poor root growth and dark green or purple-tinged leaves.

What is the role of potassium ions in plants?

Potassium ions are needed for stomatal opening.

What is a common method of pest control in agriculture?

The use of pesticides to kill unwanted species that damage crops.

How do weeds affect crop production?

Weeds compete with crops for space, water, and nutrients.

What is the impact of using pesticides on crop yields?

Pesticides help reduce damage to crops and increase yields by controlling competition from pests.

What is anaerobic respiration in yeast?

A process by which yeast converts sugars into energy without oxygen, producing alcohol and carbon dioxide.

What is the significance of industrial fermenters?

Industrial fermenters are used for large-scale production of products like alcohol and antibiotics using microorganisms.

What is the role of bacteria in yoghurt production?

Bacteria ferment lactose in milk to produce lactic acid, which thickens the milk and gives yoghurt its flavor.

What is fish farming?

The practice of raising fish in controlled environments for food production.

How can farmers balance costs and benefits when using glasshouses?

Farmers must weigh the extra costs of heating, lighting, and carbon dioxide against the potential increase in income from higher yields.

What is the importance of controlling temperature in glasshouses?

Controlling temperature prevents enzyme denaturation and maintains optimal conditions for photosynthesis.

What is the primary purpose of pesticides?

To kill unwanted species, reduce damage to crops, and increase yields.

What are the three main types of pesticides?

Insecticides (kill insects), herbicides (kill weeds), and fungicides (kill fungi).

What is a disadvantage of using pesticides?

Organisms can develop resistance, and they can harm beneficial organisms.

What is bioaccumulation?

The accumulation of persistent chemicals in great concentrations at the top of food chains.

What is biological control in pest management?

Using natural predators to reduce pest populations without completely eliminating them.

Give an example of a natural predator used in biological control.

Ladybirds eating aphids.

What is one advantage of biological control?

It is a natural method that does not cause pollution.

What is a disadvantage of biological control?

It may take longer to be effective and cannot kill the entire pest population.

What role does yeast play in food production?

Yeast is used in the production of bread through fermentation.

What type of respiration does yeast perform when oxygen is absent?

Anaerobic respiration, also known as fermentation.

What are the products of anaerobic respiration in yeast?

Ethanol (alcohol) and carbon dioxide.

How does carbon dioxide affect bread dough?

It causes the dough to rise by creating air pockets.

What happens to ethanol during the baking of bread?

Ethanol evaporates due to the heat, leaving no alcohol in the bread.

What apparatus is used to investigate anaerobic respiration in yeast?

Boiling tubes, capillary tubes, bungs, yeast, sugar solution, oil, stopwatch, water bath, and limewater.

What is the purpose of adding oil to the sugar solution in the experiment?

To prevent oxygen from entering the solution and ensure anaerobic conditions.

What is the expected outcome when yeast is placed at higher temperatures?

More bubbles of carbon dioxide should be produced, indicating faster respiration.

What is the significance of comparing results at different temperatures in the yeast experiment?

To determine the optimum temperature for yeast enzyme activity.

What is the main function of enzymes produced by yeast during bread making?

To break down starch in flour into sugars for respiration.

What is a key benefit of using biological control over chemical pesticides?

Biological control does not lead to resistance in pests.

What is a potential risk of introducing a natural predator for biological control?

The predator may become a pest itself or may not adapt to the new environment.

What is the effect of high temperature on enzyme activity during anaerobic respiration?

High temperatures can denature enzymes, slowing down or stopping carbon dioxide production.

What does CORMS stand for in practical investigations?

CORMS stands for Change, Organism, Repeat, Measure, and Control.

What is the role of Lactobacillus in yoghurt production?

Lactobacillus bacteria ferment lactose in milk, converting it into lactic acid, which thickens and sours the milk.

Why is equipment sterilized before making yoghurt?

Sterilization kills unwanted bacteria to prevent contamination and ensure the growth of Lactobacillus.

What temperature is milk pasteurized at during yoghurt production?

Milk is pasteurized at 85-95°C.

What is the purpose of cooling milk to 40-45°C before adding Lactobacillus?

Cooling allows Lactobacillus to thrive without being killed by high temperatures.

How does the acidity of yoghurt act as a preservative?

Increased acidity lowers pH, preventing the growth of harmful microorganisms.

What are industrial fermenters used for?

Fermenters are used to culture microorganisms for food production and other processes like antibiotic production.

What is the benefit of controlling conditions in an industrial fermenter?

Controlled conditions allow for the production of large quantities of specific microorganisms.

What is the optimum temperature for enzyme activity in fermenters?

The optimum temperature is maintained to ensure enzymes work efficiently without denaturing.

How is pH controlled in an industrial fermenter?

pH is monitored and adjusted using acids or alkalis to maintain the optimum level for the microorganism.

What is the significance of oxygenation in fermenters?

Oxygen is necessary for aerobic respiration to provide energy for microorganism growth.

What methods are used to ensure high yields in fish farming?

Methods include controlling water quality, managing predation, disease control, waste removal, and selective breeding.

What is the purpose of filtering water in fish farms?

Filtering removes waste and harmful bacteria, maintaining high oxygen levels for fish respiration.

How is intraspecific predation controlled in fish farming?

Fishes are separated by size and age to prevent them from eating each other.

What is the difference between intraspecific and interspecific predation?

Intraspecific predation occurs within the same species, while interspecific predation occurs between different species.

Why are antibiotics used in fish farming?

Antibiotics prevent disease spread among fish that are kept in close confinement.

How does selective breeding benefit fish farming?

Selective breeding allows for the reproduction of fish with desirable traits, enhancing growth rates.

What is the role of agitation in an industrial fermenter?

Agitation ensures even distribution of microorganisms, nutrients, and oxygen throughout the fermenter.

What happens to yoghurt after fermentation?

Yoghurt is stirred and cooled to 5°C to halt the action of Lactobacillus.

What are the advantages of fish farming over wild-caught fish?

Fish farming allows for selective breeding, predator protection, water quality control, and rapid growth.

What is the main purpose of pasteurization in yoghurt production?

Pasteurization kills unwanted bacteria that could spoil the yoghurt.

What is the significance of measuring the number of bubbles produced in yeast experiments?

Measuring bubbles indicates the rate of carbon dioxide production during anaerobic respiration.

What is the impact of controlling the concentration and volume of sugar solution in yeast experiments?

Controlling these factors ensures consistent conditions for accurate results.

How does the fermentation process affect the texture of yoghurt?

Fermentation thickens the milk, giving yoghurt its characteristic texture.

What is the importance of maintaining high levels of oxygen in fish farms?

High oxygen levels are crucial for aerobic respiration and the health of the fish.

What is the role of nutrients in an industrial fermenter?

Nutrients are essential for respiration and growth of microorganisms.

What is selective breeding?

Selective breeding, or artificial selection, is the process of selecting individuals with desirable characteristics and breeding them together.

What is the goal of selective breeding?

To produce offspring that reliably show desired characteristics over successive generations.

Name a characteristic that plants are selectively bred for.

Disease resistance in food crops.

What is one problem associated with selective breeding?

It can lead to inbreeding, which reduces the gene pool.

What is inbreeding?

Inbreeding occurs when closely related individuals are bred together, leading to a reduction in genetic diversity.

What is a consequence of a reduced gene pool?

Increased chance of organisms inheriting harmful genetic defects.

How does selective breeding affect disease resistance?

It can make organisms more vulnerable to new diseases due to fewer resistant alleles in the gene pool.

Give an example of a plant that has been selectively bred.

Wild brassica, which has given rise to cauliflower, cabbage, broccoli, Brussels sprouts, kale, and kohlrabi.

What are some characteristics for which animals are selectively bred?

High milk or meat production, large egg size, gentle nature in dogs, good quality wool in sheep, and fast pace in horses.

What is an example of an animal that has been selectively bred?

The domestic dog, which is descended from wolves.

What is the difference between natural selection and artificial selection?

Natural selection occurs naturally, while artificial selection occurs when humans intervene.

What is the outcome of natural selection?

Development of populations with features that are better adapted to their environment.

What is the outcome of artificial selection?

Development of populations with features that are useful to humans.

How long does natural selection usually take?

It usually takes a long time to occur.

How does the time frame of artificial selection compare to natural selection?

Artificial selection takes less time as only individuals with desired features are allowed to reproduce.

What should be included in exam answers about selective breeding?

The need to repeat the selective breeding process for many generations.

What is one benefit of selective breeding in plants?

Increased crop yield.

What is one benefit of selective breeding in animals?

Producing animals with desirable traits for farming or companionship.

What does selective breeding require over generations?

Selecting offspring that show desired characteristics and breeding them together.

What is the impact of selective breeding on genetic variation?

It can decrease genetic variation within a population.

What is one advantage of breeding animals from different parents?

It helps avoid inbreeding and maintains a healthier gene pool.

What is a potential risk of selective breeding in agriculture?

It may lead to a lack of resilience against environmental changes or diseases.