Wednesday, November 12, 2008

More of 13.1
Asexual Reproduction is a form of reproduction in which a single parent is involved in passing on all of its genes to its offspring. Some organisms capable of reproducing asexually are some single celled eukaryotes and the hydra (which is related to the jellyfish). Asexually reproduced organisms are similar in appearance.






Sexual reproduction is a form of reproduction in which two individuals (parents) contribute genes. This form of reproduction results in greater genetic variation in the offspring.

The Role of Meiosis in Sexual Life Cycles
  • The life cycle of an organism is defined as the sequence of stages in its reproductive history through the course of one generation.
  • Somatic cells are cells other than gametes, or egg and sperm cells. They are the body cells of an organism. Each somatic cell in humans has 46 chromosomes.
  • The karyotype of an organism refers to a picture of its complete set of chromosomes, arranged in pairs of homologous chromosomes from the largest size pair to its smallest size pair. Homologous chromosomes are those that carry the genes that contain the same traits. They are similar in length and in the position of their centromere, and they have the same staining pattern. One homologous chromosome from each pair is inherited from each parent; in other words, half of the set of 46 chromosomes in your somatic cells was inherited from your mother (she donated 230 and the other half (23) was donated by your father.

QUESTIONS

  1. A human cell with 22 autosomes and a Y chromosome is
a. a sperm
b. an egg
c. a zygote
d. a somatic cell of a male
e. a somatic cell of a female

2. How many sets of chromosomes do we inherit from our mothers?

a. 0
b. 1
c. 2
d. 3

3. The life cycle of an organism is defined as

a. maturation of the organism
b. process of asexual division of the organism
c. sequence of reproductive stages in the organisms reproductive history through the course of one generation.

4. True or False? In asexual reproduction, a single parent produces genetically identical offspring by mitosis.



answers: 1. a, 2. b, 3. c, 4. T

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