Chapter 38 — Quiz

Eighteen questions: thirteen multiple choice, five short answer. Answer key at the end with explanations.

Multiple choice

1. Approximately what percentage of the world's habitable land is currently used for agriculture?

a) About 10% b) About 25% c) About 50% d) About 75%

2. What was the approximate cost of the first laboratory-grown hamburger, unveiled by Mark Post in 2013?

a) Around $300 b) Around $30,000 c) Around $325,000 d) Around $3 million

3. Which country was the first to grant regulatory approval for cultured meat sale to consumers, in 2020?

a) United States b) Singapore c) Israel d) Netherlands

4. What was the historic problem with fetal bovine serum (FBS) as a growth medium for cultured meat?

a) It does not support cell growth b) It is expensive AND ethically incompatible with the premise of cultured meat c) It is illegal in most jurisdictions d) It is too pure for cell culture

5. Recombinant chymosin — the rennet enzyme produced by genetically engineered fungi — has been used in cheese production since approximately what year?

a) 1965 b) 1978 c) 1990 d) 2010

6. Which of the following is not a current commercial application of precision fermentation in food?

a) Recombinant insulin (medical) b) Soy leghemoglobin (in plant-based burgers) c) Beta-lactoglobulin (in non-dairy ice cream) d) Whole-cut grass-fed beef steak

7. Quorn brand mycoprotein has been commercially available in the United Kingdom since approximately what year?

a) 1962 b) 1985 c) 2002 d) 2015

8. Solar Foods produces Solein, a microbial protein, by feeding bacteria primarily on:

a) Soybeans and corn b) Hydrogen, carbon dioxide, and electricity c) Whey from dairy production d) Crystallized sugar

9. What is the role of soy leghemoglobin in the Impossible Burger?

a) A binder to hold the patty together b) A heme-iron-containing protein that catalyzes Maillard browning and provides "meaty" flavor c) A preservative d) A texture modifier

10. Which CRISPR-edited food has been approved by the US Department of Agriculture, in part because polyphenol oxidase has been knocked out?

a) Acrylamide-free french fries b) Non-browning button mushroom c) Long-shelf-life lettuce d) Pesticide-resistant corn

11. Which ancient/Indigenous tradition involves consumption of Arthrospira platensis, a cyanobacterium harvested from lakes?

a) Aztec consumption from Lake Texcoco; communities around Lake Chad b) Norse consumption from Scandinavian fjords c) Roman consumption from the Tyrrhenian Sea d) Andean consumption from Lake Titicaca

12. What is the fundamental engineering reason that cultured meat is currently more expensive than microbial protein?

a) Mammalian cells double slower than yeast or bacteria, and require more controlled growth conditions b) Mammalian cells are toxic to most bioreactors c) Cultured meat requires diamond-coated reactors d) There is no engineering difference; the cost difference is entirely regulatory

13. Food sovereignty, as articulated by La Vía Campesina, refers to:

a) The right of multinational food corporations to operate freely b) The right of peoples to define their own food and agricultural systems, including seeds, land, labor, and methods c) National food self-sufficiency through trade barriers d) Government control over all food production

Short answer

14. Explain in your own words the difference between cultured meat and precision fermentation. What is being produced in each case, and what is the role of the microorganism or cell?

15. A press release for a cultured-meat company claims that its product has "a 95% lower carbon footprint than conventional beef." What questions would you ask to assess this claim? List at least four.

16. The chapter argues that "the molecules of cooking will not change" even as new ingredients arrive. Give two specific examples from this chapter that illustrate this — cases where new technology produced a new ingredient, but the cooking science applied directly.

17. What does it mean to say that cultured meat's environmental benefits depend on the energy source for its bioreactors? Why is this an important point?

18. The chapter raises the question of whose voices should be at the table when "the future of food" is designed. Identify at least two communities or perspectives that, according to the chapter, should be included but historically have not been. Why does it matter?

Answer Key

1. (c) About 50%. Agriculture occupies roughly 50% of habitable land — a striking fraction, especially given that 77% of agricultural land is dedicated to livestock (including feed crops) but livestock provides only about 18% of global calories.

**2. (c) Around $325,000.** The Mark Post 2013 hamburger reportedly cost approximately $325,000 to produce. Costs have dropped dramatically since.

3. (b) Singapore. The Singapore Food Agency approved cultured chicken from Eat Just for commercial sale in December 2020, the first regulatory approval anywhere in the world. The US followed with USDA approval of Upside Foods and Good Meat in June 2023.

4. (b) It is expensive AND ethically incompatible. Fetal bovine serum is harvested from the blood of fetal calves; using it in cultured meat would defeat the original ethical premise. Companies have been moving aggressively toward serum-free, chemically-defined media.

5. (c) 1990. The FDA approved recombinant chymosin in 1990; it is now used in the great majority of industrial cheese production worldwide. This is the most concrete example of "precision fermentation" already at scale in food, mostly invisible to consumers.

6. (d) Whole-cut grass-fed beef steak. Whole-cut cultured meat is still an active research challenge, not a commercial product. The other three are real, current commercial uses of precision fermentation.

7. (b) 1985. Quorn launched in the UK in 1985. It launched in the US in 2002. The continuous-culture mycoprotein technology has thus been in industrial production for approximately 40 years.

8. (b) Hydrogen, carbon dioxide, and electricity. Solar Foods uses Cupriavidus bacteria, which can grow on hydrogen (produced via electrolysis), carbon dioxide (captured from air), and a few mineral nutrients. The system was originally developed for the European Space Agency for long-duration space missions.

9. (b) Heme-iron-containing protein that catalyzes Maillard browning and provides meaty flavor. Soy leghemoglobin, produced via precision fermentation of Pichia pastoris yeast, gives the Impossible Burger its meat-like browning and flavor. Heme catalyzes Maillard-type reactions at moderate temperatures.

10. (b) Non-browning button mushroom. Developed at Penn State University with a CRISPR knock-out of polyphenol oxidase. The result: a button mushroom that does not turn brown when sliced. The USDA classified this as not subject to GMO regulation, since no foreign DNA was inserted.

11. (a) Aztec consumption from Lake Texcoco; communities around Lake Chad. The Aztecs harvested spirulina (then called tecuitlatl) from Lake Texcoco for centuries before European contact. Communities around Lake Chad in Central Africa have made dried algal cakes (dihé) for many generations. Modern commercial spirulina is the same species being industrialized.

12. (a) Mammalian cells double slower than yeast or bacteria, and require more controlled growth conditions. Yeast doubles in roughly 90 minutes; bacteria in 20 minutes; mammalian muscle stem cells in 24–48 hours. Combined with the need for specialized media, low-shear bioreactors, and perfusion systems, this makes mammalian cell culture fundamentally more expensive per kilogram of biomass.

13. (b) The right of peoples to define their own food and agricultural systems. The phrase was coined in the 1990s by La Vía Campesina, a global movement of peasant farmers, Indigenous communities, and rural workers. It is a values claim about who controls food production.

14. Sample answer:

Cultured meat involves growing animal cells (typically muscle stem cells obtained by biopsy) in a bioreactor with growth medium until they form harvestable tissue. The product is essentially the same kind of cell that would have been in a conventional animal — muscle cells, fat cells, etc. — just grown without the rest of the animal.

Precision fermentation uses microorganisms (engineered yeast, bacteria, or fungi) as factories to produce specific molecules. The microbe has been given a gene that codes for a target protein (insulin, chymosin, casein, leghemoglobin, etc.); the microbe expresses that protein during fermentation; the protein is then harvested and purified. The microbe is the producer; the molecule is the product.

In short: cultured meat is the cells. Precision fermentation uses the microbes to make a specific molecule.

15. Sample answer questions:

  • What is the comparison being made? (Cultured beef vs. what kind of conventional beef? Beef raised in what way? In what country? With what feed?)
  • How was the carbon footprint calculated? (Life-cycle analysis methodology? Cradle-to-gate or cradle-to-grave? Who performed it?)
  • What energy source is being assumed for the bioreactor? (Renewable electricity? Grid average? In which region's grid mix?)
  • Has the analysis been peer reviewed?
  • Is the comparison at production scale, or at lab scale?
  • What were the boundary conditions? (Are growth-medium production emissions included?)
  • Was the analysis funded by the cultured-meat company itself?

16. Sample answer:

Two examples from the chapter:

  • The Maillard reaction works on plant-based burgers (Impossible, Beyond) and on cultured meat in essentially the same way it works on conventional meat. The chemistry of amino-acid + reducing-sugar → flavor compounds is the same; what differs is the precise composition of starting materials. Therefore the cooking technique (high heat, brown the surface) is the same. Similarly, browning works on mycoprotein (Quorn) because mycoprotein contains the same kinds of amino acids and reducing sugars as meat.

  • Precision-fermented chymosin (cheese rennet) acts on milk protein in exactly the same way calf-derived chymosin does. The cheesemaking process — temperature, acid, time — is unchanged. Cheesemakers transitioning from animal to microbial rennet have not had to relearn cheesemaking; they have just used a different bottle of enzyme.

In both cases, the molecules and reactions of cooking apply to the new ingredient as they did to the old. The cook adapts; the science transfers.

17. Sample answer:

A bioreactor is a large heated, oxygenated, stirred vessel that requires substantial continuous electricity to operate (for heating, stirring, oxygen delivery, refrigeration of media, separations, packaging, etc.). The total carbon footprint of cultured meat is the sum of feedstock emissions (the inputs to the bioreactor — sugars, growth factors, etc.), the embedded emissions of the equipment, and the operational emissions of the electricity and other energy used.

If the electricity comes from coal-fired power plants, cultured meat may not be carbon-better than conventional beef — and recent peer-reviewed life-cycle analyses have found this. If the electricity comes from renewable sources (solar, wind, hydroelectric), cultured meat can be substantially better than conventional beef.

This is important because it means cultured meat's environmental advantage is not a property of the product alone — it is a property of the electricity grid in which the product is made. The decarbonization of the electricity grid is therefore a precondition for cultured meat to deliver its promised benefits at scale. The two technological projects (cultured meat and grid decarbonization) are linked.

18. Sample answer:

Communities and perspectives that, according to the chapter, should be at the table but historically have not been:

  • Indigenous peoples — including the Indigenous Peoples of the Americas (whose food systems gave the world maize, potatoes, tomatoes, chocolate, vanilla, and many other staples), Indigenous Australian peoples, Indigenous African pastoralists and farmers, and many others. Indigenous food sovereignty movements articulate that food futures must include and respect cultures' food traditions, not impose top-down "solutions."

  • Smallholder farmers globally, particularly in the Global South. Most of the world's farmers are smallholders. Many of them grow the crops (cocoa, coffee, vanilla, palm oil, sugar) on which the global food economy depends. Their livelihoods are at stake when "alternative" technologies replace what they grow. The development of lab-grown coffee, in particular, is a flashpoint — millions of livelihoods could be displaced.

  • Food-insecure communities — the people for whom the arithmetic problem is not a thought experiment but a daily reality. The technologies in this chapter are being developed and deployed in wealthy regions; the people who would benefit most from cheaper, more nutrient-dense food may be the last to get it.

  • Cultural communities for whom specific foods carry identity, ceremony, or meaning — for whom replacing the food with a microbial alternative is not a neutral substitution.

Why it matters: The food system that has just been described as needing to change is itself the product of historical patterns of land use, labor, and trade in which some communities benefited and others bore costs. If the "solutions" are designed by the same kinds of institutions that designed the problem, the harms of the transition can fall on the same people. Including more voices is not a matter of ceremony; it is how the technology gets developed in directions that improve the harms-distribution, rather than perpetuating it.