وراثت اور خلیاتی تقسیم

Written by Dr. Hira Salman (Biology)

ایم ڈی کیٹ · حیاتیات · 10 سوالات

نام: ____________________ تاریخ: ____________

In which phase of mitosis do the chromosomes line up at the equator of the cell?
- A Metaphase
- B Prophase
- C Anaphase
- D Telophase
Crossing over takes place during:
- A Interphase
- B Metaphase of mitosis
- C Prophase I of meiosis
- D Anaphase II of meiosis
How many chromosomes are present in a normal human gamete?
- A 46
- B 23
- C 92
- D 44
A cross between two heterozygous tall plants (Tt x Tt) gives tall and short offspring in the ratio:
- A 1 : 1
- B 3 : 1
- C 1 : 3
- D 9 : 3
Which base pairs with adenine in DNA?
- A Uracil
- B Cytosine
- C Guanine
- D Thymine
A test cross is used to find the genotype of an individual by crossing it with:
- A A homozygous recessive individual
- B Any unrelated individual
- C A homozygous dominant individual
- D A heterozygous individual
Down syndrome is caused by:
- A Monosomy of chromosome 21
- B Loss of the Y chromosome
- C A missing X chromosome
- D Trisomy of chromosome 21
Which experiment demonstrated that DNA replication is semi-conservative?
- A Hershey and Chase
- B Griffith's experiment
- C Meselson and Stahl
- D Mendel's pea crosses
Haemophilia is inherited as:
- A An autosomal recessive trait
- B A Y-linked trait
- C An X-linked recessive trait
- D An autosomal dominant trait
The offspring of AaBb x AaBb (independent assortment, complete dominance) show a phenotypic ratio of:
- A 3 : 1
- B 1 : 1 : 1 : 1
- C 1 : 2 : 1
- D 9 : 3 : 3 : 1

جوابی کلید

1. A, 2. C, 3. B, 4. B, 5. D, 6. A, 7. D, 8. C, 9. C, 10. D

In metaphase the chromosomes line up on the metaphase plate. In anaphase the sister chromatids separate.
Homologous chromosomes pair up in prophase I and exchange segments. This produces new combinations of alleles.
Human body cells have 46 chromosomes. Meiosis halves this, so each gamete has 23.
The offspring are TT, Tt, Tt and tt in the ratio 1:2:1. TT and Tt are tall, so tall to short is 3:1.
In DNA, adenine pairs with thymine by two hydrogen bonds, and guanine pairs with cytosine by three. Uracil replaces thymine in RNA.
Crossing with a homozygous recessive shows the unknown parent's alleles in the offspring. Any recessive offspring means the parent carries a recessive allele.
Down syndrome results from three copies of chromosome 21, usually through non-disjunction in meiosis.
Meselson and Stahl used heavy nitrogen to show that each new DNA molecule keeps one old strand and gets one new strand.
The gene is on the X chromosome. Males have one X, so one recessive allele is enough to show the disease, which is why it is more common in males.
This is Mendel's dihybrid cross. The four phenotypes appear in the ratio 9:3:3:1.