Question Video: Describing the Difference between Monocot and Dicot Seeds | Nagwa Question Video: Describing the Difference between Monocot and Dicot Seeds | Nagwa

Question Video: Describing the Difference between Monocot and Dicot Seeds Biology • Third Year of Secondary School

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What is the difference between the structure of monocotyledonous and dicotyledonous seeds?

02:56

Video Transcript

What is the difference between the structure of monocotyledonous and dicotyledonous seeds? (A) In dicots, the endosperm food store is moved into the cotyledons. (B) In dicots, two embryos develop within the endosperm. (C) In dicots, there is twice as much endosperm as monocots. (D) In dicots, the starch of the endosperm is broken down into sugars. Or (E) in dicots, the endosperm contains less water than monocots.

Angiosperms are flowering plants. There are two main types of angiosperms: monocotyledons, also known as monocots, and dicotyledons, also known as dicots. A cotyledon is a structure within the angiosperm’s seed that eventually becomes the plant’s first leaf. The prefix mono- means one and di- means two. So, while monocotyledonous seeds have one cotyledon, dicotyledonous seeds have two cotyledons. Let’s remove the answer choices for now so that we have some more space to take a look at seed’s anatomy.

A seed has a seed coat, which protects the plant embryo within the seed. A plant embryo contains the earliest forms of a plant’s root, stem, and the cotyledon or cotyledons. Monocot plant seeds also contain a food store called an endosperm, which provides the seedling with food after it breaks out of the seed coat. So the seedling does not have to start to photosynthesize immediately. In dicotyledons, the two cotyledons have often absorbed the endosperm before the embryo breaks out of the seed coat. This means that the plant will rely on photosynthesis in these first leaves to provide the seedling with nutrients.

Now, let’s take a look back at our answers. First, we can eliminate answer (B). In dicots, there are two cotyledons within the embryo, not two embryos. We can eliminate answer (C) as well, as we know that there is more endosperm in monocots, as in dicots the two leaves absorb most of the food store. Dicots would therefore have less, not two times more, endosperm than monocots.

We can also eliminate answer choice (D). In dicots, the endosperm is used for the development of the two embryonic leaves, not to produce sugars. Finally, we can eliminate answer (E). It is not necessarily true that the endosperm contains less water in dicots compared to monocots. In fact, in many dicots, there is no endosperm left toward the end of embryo development. We can’t compare the water content of an endosperm in monocots to a nonexisting endosperm in dicots.

As we have learned that in dicots the two embryonic leaves, or cotyledons, absorb the endosperm, we know that the correct answer must be (A). In dicots, the food store is moved into the cotyledons.

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