Biology Chapter 17
Terms
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- The oldest living organism on Earth is the ____________ which was estimated at ____________ years old.
- Bristlcone pine tree, 4600
- In the early 20th century the life expectancy was ____________ years old and today it is much greater (77-81 years), which can be attributed to ____________ advances.
- 50, technological
- ICSI is a fertilization technique where _____________ is directly injected into the _____________.
- sperm, egg
- Forming the __________ is the first step of the life cycle.
- blastocyst
- The Giant clam releases ____________ first into the ocean and then waits 30 minutes before releasing the __________________, this helps to avoid self-fertilization.
- Sperm, egg
- The Christmas Island crabs make a pilgrimage to the shore to lay their ____________ in the ocean even though they reside on _______________.
- eggs, land
- Placental mammals evolved a ____________ which allows them to develop a fertilized egg into a fully-formed animal.
- uterus
- After fertilization the embryo attaches to the uterus and produces the _______________ which will transfer the nutrients gained from the mother to the fetus.
- placenta
- The maximum _______________ ______________ represents the biological limit of a species.
- Life span
- What is the “maximum life span†and give 4 examples of how it differs between species.
- The maximum life span represents the biological limit of a species. Different species live to many different ages. (For the 4 examples refer to life span table, i.e. bristlecone pine = 4900 yr, human=122 yr, cat – 21 yr, earthworm = 10 yr)
- How was the age of the bristlecone pine determined and how did this help in understanding history?
- The age of the bristlecone pine was determined using a cross section of the tree. The number of rings in that cross section were counted with each ring representing one year of life. Inspection of the width of the can tell us what kind of year the tree had (whether the climate promoted growth or not). Hidden within the trunk was a record of weather and time, a history of the past.
- What factors determine the life expectancy and what has contributed to the increase in longevity?
- How long an individual lives is determined by environmental factors such as availability of food and presence of predators. Improvements in the living standards of many countries has resulted in a significant increase in longevity.
- What are the three types of mammals? What are their different ways of giving birth?
- The three types of mammals are monotremes, marsupials and placenta mammals. The monotreme mammals retain the reptilian way of giving birth by laying eggs. The marsupial and placenta mammals give birth to live young.
- Why are placental mammals so successful?
- The success of placental mammals comes from the ability of the mother to carry its young internally for many months. The mother remains active and retains her normal activity. Placenta mammals have evolved a uterus allowing them to develop a fertilized egg into a fully-formed animal.
- Distinguish between the terms life expectancy and life span. The Pacific Sockeye Salmon provides and excellent demonstration of the various components of the life cycle. Explain the components of the life cycle and describe each phase using the salmon as
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Life Span: biological characteristic which remains fixed among members of a species and depends upon reproductive strategies.
Life expectancy: is subjected to environmental factors which can very depending upon the living conditions.
Organisms must live long enough to reproduce. They are born, grow, reproduce, and die.
The salmon are born in remote streams in the Canadian Rockies. The smolts spend the 1st 3-4 years of their life in fresh water. The grow and migrate along streams and rivers to the ocean. They spend another 3-4 years feeding and growing into sexually mature fish. They then migrate thousands of miles from the ocean to their birth place. Once they reach their destination the female digs a nest and lays 50-100 eggs. The males fight to fertilize the female’s eggs. Within days of reproducing the fish die.