Lesson video

Good day, my name's Mrs. Harking.

The title of today's lesson is A solution: Genetically modified crops, taken from the unit Natural resources: can Earth meet our needs?

In today's lesson, we'll be exploring the advantages and disadvantages of GM crops, and some of the disadvantages are things that you may not have predicted would happen.

It will be interesting to learn this with you today.

Let's get started.

Our outcome today is to assess the advantages and challenges of genetically modified crops in tackling global food issues and environmental pressures.

Before we start the lesson, it's a good idea to look at these four keywords that are going to come up in the lesson today.

First of all, we have GM crops.

We'll define this later in the lesson as well in a little bit more detail.

But just so you know for now, GM crops are plants whose genes have been altered in a laboratory to give them improved traits.

Yield is the amount produced, especially in farming.

Pesticides are substances that are added to the soil or sprayed on plants to protect plants from pests such as insects.

Herbicides are substances that are added to the soil or sprayed on plants as well, but this time they are to protect plants from weeds.

If there's any of those that you'd like to make a note of, feel free to pause the video and do that now.

Our lesson today is in two parts: firstly, benefits of GM crops, and secondly, challenges of GM crops.

We'll start with the benefits.

So what are GM crops?

We need to have a look at the words involved in the name and break it down so we can fully understand it.

So firstly, we've got genetically.

Anything to do with genetics is related to genes which determine the traits like yield.

We'll look a little bit more at what genes means in a moment.

Modified means to improve or adjust something.

And crops mean plants grown by farmers for food or other useful products.

You probably knew that one.

So genetically modified crops.

We're going to have a closer look now at that genetic side of things.

Organisms are made up of cells.

The nucleus of a cell contains many chromosomes.

The chromosomes contain DNA.

And a gene is a section of DNA where the code for a trait is found.

A trait in humans could be something like eye color or hair color.

A trait in plants could be something such as size of the plants or how many fruits that plant produces.

GM crops are plants whose genes have been altered in a lab to give them improved traits.

Time for a check for understanding now.

Select the correct definition of GM crops.

Is it A, plants whose leaves have been altered in a lab to improve them?

B, plant who's genes have been altered in a lab to make them grow larger?

Or C, plants who's genes have been altered in a lab to give them improved traits?

Well done.

Yes, it's C.

Plants who's genes have been altered in a lab to give them improved traits.

Changes to genetic traits of crops can lead to one or more of the following benefits: higher crop yields.

For example, if you had a tomato plant, that might mean that that one plant produces more tomatoes.

Pest resistant, meaning reduced need for chemical pesticides, remembering that pesticides are chemicals which kill pests or prevent pests from eating plants in some way.

More nutritious crops.

Nutritious means full of nutrients.

And crops can grow in harsh conditions.

So sometimes the genetically modified crops will be more tolerant to drought or poor soil.

Also, foods might have a longer shelf life.

And this is an example you can see on the right-hand side when we compare organic tomatoes to GM tomatoes.

Finally, lower production costs for farmers.

And that's partly because of the higher crop yields and less need for pesticides.

So how can GM crops improve nutrition?

Well, there's one example.

If we look at vitamin A deficiency, this was a major public health issue in the 1990s, especially in Southeast Asia.

It caused blindness and death in children dependent on the rice-based diet.

We can see a map here which shows us the prevalence of children who have vitamin A deficiency, and this is between 1995 and 2005.

When we have a look at the scale at the bottom, it shows us the percentage of children who had a low vitamin A concentration.

So if we have a look, we can see that actually it's not just Southeast Asia.

We can also see there's many areas of Africa as well that have higher percentages of children who do suffer from this deficiency.

The GM solution that was provided was golden rice.

It was first created in 1999 by scientists who inserted genes enabling the rice to produce beta-carotene, and this is a source of vitamin A.

Rice was chosen because it's a staple food for over half the world's population, but it normally lacks vitamin A.

One portion of golden rice can provide 60% of a child's daily vitamin A requirement.

However, since it is not widely approved and used, it's too early to see public health improvements such as declines in blindness.

So there's a lot of potential here for real world-changing impact.

Time for a check for understanding.

What traits did genetic engineering introduce to golden rice?

Was it A, higher crop yields?

B, pest resistance?

C, more nutritious crops?

Or D, can grow in harsh conditions?

Well done.

Yes, it was more nutritious crops.

Which specific vitamin deficiency is golden rice designed to reduce?

Yes, well done, it's the vitamin A deficiency.

How can GM crops increase yields by resisting pests?

Well, the stalk borer pests, mainly caterpillars, were causing major crop losses in South Africa in the 1990s.

We can see a diagram here of a caterpillar stalk borer boring into the stalk of a plant, and here is also a photograph to show you what do those look like in color.

Bt maize was introduced in South Africa in 1998.

It contains genes from bacteria, which produce toxins poisonous to certain insects but which are safe for humans and animals.

This means pests, like the European corn borer, die when they feed on the plants.

Bt maize improved food security and income for many rural communities.

Small-scale farmers reported higher yields and less pest damage.

The use of GM helped lower pesticide use, benefiting the environment and improving health for farmers and consumers.

Here we'd say when we're talking about consumers, we're talking about people who are buying that food that's made from that crop.

Time for a check for understanding now.

Can you fill in the gaps?

Bt maize contains from bacteria which produce toxins to certain but which are safe for humans and animals.

Small-scale farmers reported higher and less pest damage.

What is it that fill in those gaps?

I'll give you five seconds now.

If you need to pause the video, 'cause you might need a little bit longer, that's absolutely fine.

Well done, everyone.

Let's take a look at some answers.

First, Bt maize contains genes from bacteria, which produce toxins poisonous to certain insects but which are safe for humans and animals.

Small-scale farmers reported higher yields and less pest damage.

Did you get them right?

Good try.

Well done.

Time for our first task today.

Firstly, I would like you to correct the two mistakes in this definition of GM crops.

It says GM crops are plants whose leaves have been altered in a lab to improve them.

So one of the mistakes is incorrect, and the other one is just you could improve this wording.

It's not the best wording to use.

Secondly, I'd like you to imagine your job is supplying South African farmers with seeds and other farming supplies.

I'd like you to give a customer three reasons why they should buy Bt maize seeds.

Feel free to pause the video now to give yourself time to do the task.

I'll check back in with you shortly.

Well done, everyone.

Let's take a look at some answers.

So firstly, our definition should look something like this.

So GM crops are plants whose genes, not leaves, genes, have been altered in a lab to improve their traits, so "improve them" is a bit vague.

We would say their traits are being improved because that is a specific term used in connection with genetic alteration.

We're going to give an example here.

So higher crop yields and pest and drought resistance are good examples to add.

You may have added something else.

For question two: you sell farming supplies, give the customer three reasons why they should buy Bt maize seeds.

Your answer may include: so you could have had Bt maize is genetically modified to prevent the stalk borer pests.

You may also have said that less money will be needed for pesticides, and this will also improve the health of farmers and consumers as well as the environment.

Small-scale farmers reported higher yields, so you could also mention that.

Did you get all of that?

Feel free to pause the video now to add anything that you'd like to.

Now moving on to the second part of our lesson: challenges of GM crops.

The use of GM crops is a contentious topic that has created a lot of debate.

For example, at this protest, people might be saying, "What if they crossbreed with wild plants?

" "It just isn't ethical to alter nature.

" "We don't know what long term health issues GM crops could create.

" "Big businesses could end up controlling seed supplies and have too much power.

" "Some pests may develop resistance over time.

" Let's take a look at some of these in a little bit more detail.

Sofia asks, "Why would cross-breeding be a problem?

" Super weeds.

It's all to do with super weeds.

So these could inadvertently appear if herbicide, remember that's chemicals that kill weeds, herbicide-tolerant GM crops crossbreed with wild relatives, then super weeds could be produced that are resistant to the chemicals used to kill them, which wouldn't be so good.

This could lead to wild plants that are harder to control, requiring stronger or more varied herbicides, which undermines the goal of reducing the chemical use in the first place, doesn't it?

So that is a genuine problem that could be quite problematic.

That was the goal there.

Alex says, "Have the crops not been tested to ensure there are no health issues?

" So most scientific bodies, like the World Health Organization, have found no conclusive evidence of harm from approved GM foods, which have all been tested, which is very reassuring.

However, some animal studies raise questions, and critics argue that long term human studies are limited, and this is also quite contentious.

So we don't have enough scientific data yet to be able to say that actually, long-term, there'll be no health issues in people that do consume GM crops.

So as per usual, two sides to every argument.

Time for a check for understanding.

All the tests run on GM crops have found that they create no health issues.

That is false.

Can you tell me why?

Yes, so most scientific bodies, like the World Health Organization, find no conclusive evidence of harm from approved GM foods, which have all been tested.

However, some animal studies raise questions, and critics argue that long-term human studies are limited.

Jacob asks, "Have pests actually developed resistance?

" Bt cotton was introduced in India in 2002 to combat the bollworm infestations.

The bollworm is a pest that can cause damage to crops.

Initially, it boosted yields and reduced pesticide use.

Very positive.

Over time, however, bollworms developed resistance, and secondary pests emerged, leading to renewed reliance on pesticides.

So the whole purpose of using the GM crops was defeated because in the end they did have to use pesticides anyway.

Quick check for understanding.

Which of the following statements is incorrect?

Is it A, Bt cotton initially boosted yields and reduced pesticide use?

B, bollworms developed resistance to Bt cotton?

C, Bt cotton became more resistant to bollworms?

Or D, pesticides now have to be used to prevent bollworms in Bt cotton crops?

Well done.

Yes, so the incorrect statement was Bt cotton became more resistant to bollworms.

That's not what happened, was it?

It was the other way around.

Jun asks, "Can't farmers just save some seeds from plants each year instead of buying from big businesses?

" He's really confused about the fact that big businesses might become too powerful and control the seed supply.

So when farmers buy most GM seeds, they typically sign agreements that prevent them from saving and replanting those seeds.

Many seeds saved from the GM plants often produce weaker or unpredictable offspring anyway.

So actually, if you do farm with these crops, you do have to buy the seeds each year, which is a cost.

Bt cotton farmers in India face rising seed costs and inconsistent results, especially in drought-prone areas.

Some farmers experience financial stress as well.

Time for a check for understanding.

Bt cotton was a success.

True or false?

Well done.

That is false.

Can you tell me why?

Yes, Bt cotton initially boosted yields and reduced pesticide use.

Over time, however, bollworms developed resistance, and secondary pests emerged, leading to renewed reliance on chemical treatments.

Bt cotton farmers in India face rising seed costs and inconsistent results, especially in drought-prone areas.

What do you think?

Should we grow GM crops?

Feel free to pause the video now to discuss.

Time for our final task now.

Can you evaluate the benefits and challenges of using genetically modified GM crops, with reference to named examples?

I put some pictures on the slide here to help you remember those examples that we discussed.

I would suggest that you write a short introduction briefly telling me what GM crops are.

Then give me one paragraph on the benefits of GM crops, using examples, one paragraph on the challenges of GM crops, using examples, and then a very short conclusion just saying whether you think the benefits outweigh the challenges.

Pause the video now to give yourself time to do the task.

Well done, everyone.

Let's take a look at some answers.

So your answer may look like this: GM crops are plants whose genes have been altered in a lab to give them improved traits.

They offer benefits but also raise concerns.

Benefits of GM crops include improved nutrition, for example, golden rice helps reduce vitamin A deficiency, which can reduce risk of blindness and deaths in children.

Bt maize lowers pesticide use, protecting farmers and consumers.

These crops can boost food security, health, and income.

However, there are many challenges associated with GM crops.

For example, pests developed resistance to Bt cotton in India.

In addition, GM traits may spread to wild plants, creating super weeds which require stronger herbicides.

GM crops offer clear benefits, but long-term success is still uncertain.

How did your answer compare?

If there's anything you'd like to take to use to edit your own answer, feel free to pause the video and do that now.

Well done, everyone.

Now we're onto our summary.

GM crops are plants whose genes have been altered in a lab to give them improved traits.

GM crops can offer higher yields, pest resistance, improved nutrition, climate resilience, longer shelf life, and lower costs.

Bt maize improved food security and income for many rural communities.

Concerns over GM crops include breeding of super weeds, long-term health issues, resistant pests, and big businesses holding too much power.

Bollworms developed resistance to Bt cotton in India.

I hope you enjoyed learning with me today.

See you next time.

Bye.