Comprehension:
In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in
each blank.
Deoxyribonucleic acid (DNA) is a very special molecule. It (1)__________________ as the code for all life on Earth, holding the
cellular instructions to (2)______________ everything from a beetle to a human. Because DNA is (3)_________________ to each
species, it’s like a product barcode in a supermarket. As animals and plants live their lives, they (4)________________ fragments of
their DNA into their environment (5)_________________ dead skin, hair, saliva, scat, leaves or pollen. These traces make up
environmental DNA. There’s enough DNA in water and even air to tell species apart.
Select the most appropriate option to fill in blank no. 4.
