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Limits to Cell Size DNA Overload • As the cell grows, the
DNA does not so there becomes an “information crisis”. o There is a greater demand
on the “genetic library”.
Limits to Cell Size Exchanging Materials • As the cell increases in size It becomes very difficult to get
food, water, oxygen to all parts of the cell and difficult to remove waste.
• This rate of exchange depends entirely on the “surface area” and “volume” of the cell.
Division of the cell • Before the cell becomes too
large, it will divide to INCREASE the surface are/volume ratio. o This will make the cell MORE
efficient as the exchange of materials (food, water, oxygen, waste)
o Each cell will get a COMPLETE copy of the genetic material (DNA).
Comparing Asexual and Sexual Reproduction
Asexual Reproduction • The production of genetically identical offspring
from a single parent. One cell divides into two. • Occurs in many single celled organisms. (bacteria &
protozoans) • Some multicellular organisms, like Hydra, will
produce a “bud” which is also a form of this type of reproduction.
• Allows the organism to reproduce quickly, but can be a disadvantage if environmental conditions change because genetically identical individuals CAN’T adapt quickly.
Comparing Asexual and Sexual Reproduction
Sexual Reproduction • Fusion of two separate parent cells called
“reproductive cells – sperm/egg”. • The offspring inherit some characteristics
from each parent. • Most animals/plants reproduce in this way. • Allows genetic diversity, so some
individuals may survive if environmental conditions change.