LONDON (AP) ― At a public tasting in London on Monday, Dutch scientists served a single hamburger made from cow stem cells. Some questions and answers about the science behind the revolutionary patty, how it could help combat climate change and what it actually tastes like.

Q: What are stem cells?

A: Stem cells are an organism’s master cells and can be turned into any other cell type in the body, i.e. blood, tissue, muscle, etc. Adult stem cells are found in small numbers in most human tissues, including bone marrow, fat and muscle.

Q: Why is the meat so expensive to produce?

A: The technology is new and scientists are making very small quantities of meat. There are no economies of scale to offset the initial high costs. If more scientists or companies start using the technology to produce more meat products, that could drop the price substantially and speed up its production.

Q: When could this meat be in stores?

A: Probably not for another 10 to 20 years. It would take years to refine the technology, encourage other producers and scientists to get involved, and overcome any regulatory issues.

Q: Who paid for the research?

A: Sergey Brin, co-founder of Google, underwrote the 250,000 euro ($300,000) project, which began in 2006. The Dutch government previously donated 2 million euros to the research.

Q: How is this better for the environment?

A: It could reduce the number of animals needed for the meat industry. Raising cows, pigs, chickens, etc., contributes substantially to climate change through the production of methane gas. Growing meat in the laboratory could reduce the impact on agricultural land, water and resources.

Q: How long does it take to grow a burger?

A: At the moment, a long time. It has taken two years for scientists to refine the process to grow enough meat. To actually grow enough meat for a couple of burgers would probably take about eight weeks. Actually forming the lab-made meat into a hamburger patty takes about two hours because scientists must put many separate strands together.

Q: What does the process involve?

A: Scientists first take a sample of muscles from a cow in a process they say is a painless biopsy. They then put those cells into a nutrient solution that helps them reproduce. After that, they are placed into a donut-shaped dish where the cells organize themselves into bits of muscle tissue. Electrical stimulation is sometimes used to exercise the muscle cells, which flex spontaneously. Once there are enough strands of meat (about 20,000 small strands), scientists can make a five-ounce (140-gram) hamburger.

Q: What are the implications for vegetarians?

A: PETA, People for the Ethical Treatment of Animals, supports attempts to grow meat in labs.