Sbi3U Exam Review

Topics: Meiosis, Mitosis, Blood Pages: 25 (4731 words) Published: July 10, 2013
Biology Exam 2013 - Review


Describe Mendel’s experiments:
* Chose a female parent; chooses a male parent; pollen is collected from the stamens and dusted onto the female parent stigma; pollen fertilizes the eggs. The ovary develops into the pod and eggs develop into the peas; when peas are planted they develop into pea plants.

Why Pea Plants?
* Easily obtained
* Grown quickly; several generation of peas can be observed * Traits are easily visible
* Pea flower is closed. This prevents cross-pollination.

Relationship between Dominant and Recessive Traits:
Dominant: the form of a trait that always appears when an individual has an allele for it Recessive: the form of a trait that only appears when an individual has two alleles for it

Trait: a specific characteristic or feature exhibited by an organism

True breeding: organisms that exhibit the same traits, generation after generation

Cross: the fertilization of a female gamete of specific genetic origin with a male gamete of specific genetic origin

Monohybrid crosses: a cross of two individuals that differ by one trait

Allele: one or two more forms of a gene

What does the law of dominance state? How do Mendel’s experiments prove this? * The law of dominance states that if a dominant allele is present, only the dominant form of the trait will be expressed. * Proved this through the recessive green trait and the dominant yellow trait

Homozygous and heterozygous and genotype and phenotype:
* Homozygous: an organism that has two identical alleles of a gene; i.e. (YY or yy) * Heterozygous: an organism that has two different alleles of a gene; (Yy) * Genotype: the combination of alleles for any given trait, or the organism’s entire genetic make-up * Phenotype: the physical and physiological traits of an organism

What is the law of random segregation?
* Traits are determined by pairs of alleles that segregate during Meiosis so that each gamete receives one allele

KNOW*** monohybrid crosses, dehydrate crosses, incomplete dominance, multiple alleles and co dominance and sex linked problems.

What is the difference between each of these crosses?

Identify sex-linked traits: (255)
* If a gene is found on the X chromosome (and less commonly on the Y chromosome) it is said to be a sex linked trait

Red-green color vision deficiency X-LINKED RECESSIVE

Duchene muscular dystrophy X- LINKED RECESSIVE


Hairy ears Y - LINKED

* The study of the likely hood of the occurrence of a particular event or offspring

Why is it important to use a punnet square?
* They are there to help you understand the probability of a potential offspring you can get from 2 different parents * i.e. the probability of a homozygous recessive brown eyed women and a heterozygous blue eyed man’s child ------------------------------------------------------------------------------------------------------------------------------------------


* Consists of two molecules that form a ladder type structure called a DOUBLE HELIX * A molecule of DNA is made up of millions of subunits called NUCLEOTIDES building blocks of DNA

NUCLEOTIDES consist of:
1) Phosphate group
2) Pentose Sugar
3) Nitrogenous base

* The phosphate and sugar form the backbone of DNA molecule, where as the bases form the rungs

1) Adenine (A)
2) Thymine (T)
3) Cytosine (C)
4) Guanine (G)

* Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand * To crack the code found in DNA we need to look at the sequence of bases; they are arranged in TRIPLETS called CODONS AGG – CTC – AAG – TCC – TAG


* A gene is a section of DNA that...
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