YEAR 10 SCIENCE HOMEWORK – 2 / EVOLUTION
DNA and Genetic Inheritance
Almost every cell in all living organisms has a set of chromosomes. These
long thread-like structures store the DNA molecules that contain all the
information needed to make cells work. This information is passed on
from one generation to another when a cell divides.
The structure of DNA was worked out in 1953 by James Watson and
Francis Crick, in what became one of the most famous scientific
discoveries of modern science. A DNA molecule is made up of two strands,
which twist around each other to form a shape called the double helix. The
strands are held together by the bases, which always pair up precisely.
These are called base pairs.
When a cell divides, its DNA molecules copy themselves, or replicate, in order to pass on a set of
instructions to each new cell. During replication, each DNA molecule 'unzips' itself, so that its
strands separate. The two strands then form complementary (matching) copies of themselves.
Two new DNA molecules are produced, each with one old strand and one new strand.
Write all answers in full sentences.
1. Describe how the chromosomes look like as described in the passage.
2. When does genetic information pass from one generation to another?
3. What was one of the most famous scientific discoveries of modern science?
4. Describe the double helix.
5. Describe briefly as to what happens during DNA replication
.
 QUIZ- Write true or false next to each statement
1. Chromosomes are not present in all the cells__________
2. The DNA molecule contains very vital genetic information ____________
3. The DNA molecule was discovered by only one scientist _____________
4. The structure of DNA has two twisted strands ______________
5. During cell division, the DNA molecule makes an exact copy of itself ______________
Paste this homework sheet in your science book.