Which of the processes, sexual reproduction or asexual reproduction, bring about maximum variations in the offsprings?
Mendel said that the characteristics or traits of organisms are carried from one generation to the next by internal factors which occur in pairs. What is the modern name for these factors?
Some plants occur in one of the two sizes: tall or dwarf. This characteristic is controlled by one pair of genes. Tallness is dominant to dwarfness. Choose suitable letters for this gene pair.
State whether the following statement is true or false:
The sex of an infant is not a case of inheritance of characteristics.
Name one reptile in each case where higher incubation temperature leads to the development of: (a) male progeny, (b) female progeny.
Fill in the following blanks with suitable words:
(a) Genes always work in ___________
(b) In pea plants, the gene for dwarfness is ___________ whereas that for tallness is ___________ .
(c) Most people have ___________ earlobes but some have ___ earlobes.
(d) A human gamete contains ___________ chromosomes whereas a normal body cell has ___________ chromosomes in it.
(e) All races of man have __________blood groups.
(f) The. ___________chromosomes for a ___________are XX whereas that for a________ are XY.
Which of the following represent tall plants and which represent short plants (or dwarf plants)?
Give a reason for your choice (The symbols have their usual meaning).
A man having blood group O marries a woman having blood group B and they have a daughter. What will be the blood group of the daughter?
(a) State one advantage of variation to a species. (b) What are sex chromosomes? How many sex chromosomes are there? Name them.
In the F2 generation of a cross, progeny having different traits are produced in the ratio 3:1. State whether it is a monohybrid cross or a dihybrid cross? Give one example of such a cross.
(a) If a normal human cell has 46 chromosomes, how many chromosomes will be there in a human (i) sperm cell, and (ii) zygote?
(b) What sizes of plants are produced if both parents have genes Tt?
Gregor Mendel's first law of genetics states "Of a pair of contrasted characters, only one can be represented in a gamete by its internal 'factor'.
(a) Give the modern name for this 'factor'.
(b) State where these factors are found in gametes.
(a) What is meant by 'heredity'? What are the units of heredity?
(b) State Mendel's first law of inheritance.
(a) What do you understand by the term 'variation'?
(b) Name two human traits which show variation.
(c) How does the creation of variation in a species ensure its survival?
(a) What are genes? Where are they located in our body?
(b) What is meant by dominant genes and recessive genes? Give one example of each.
(c) Explain how characteristics (or traits) are inherited through genes.
(a) How do Mendel's experiments show that traits may be dominant or recessive?
(b) How do Mendel's experiments show that traits are inherited independently?
A cross between two individuals results in a ratio of 9 : 3 : 3 : 1 for four possible phenotypes of progeny. This is an example of a :
(a) dihybrid cross
(b) monohybrid cross
(c) test cross
(d) none of these
For his experiments on heredity, Mendel used:
(a) papaya plants
(b) potato plants
(c) pea plants
(d) pear plants
In order to ensure that he had pure-breeding plants for his experiments, Mendel :
(a) cross-fertilized each variety with each other
(b) let each variety self-fertilize for several generations
(c) removed the female parts of the plants
(d) removed the male parts of the plants
In the human blood grouping, the four basic blood types are type A, type B, type AB, and type O. The blood proteins A and B are:
(a) simple dominant and recessive traits
(b) incomplete dominant traits
(c) codominant traits
(d) sex-linked traits
A pregnant woman has an equal chance of her baby being blood group A or blood group AB. Which one of the following shows the possible genotypes of the woman and the father of her child?
(a) I^AI^A\ and\ \ I^BI^O
(b) I^AI^B\ \ and\ I^BI^O
(c) I^AI^O\ and\ I^BI^O
(d) I^AI^B\ and\ I^AI^O
The visible characteristic in an organism is known as:
The exchange of genetic material takes place in:
(a) vegetative reproduction
(b) asexual reproduction
(c) sexual reproduction
A cross between a tall plant (TT) and short plant (tt) resulted in progeny that were all tall plants because :
(a) tallness is the dominant trait
(b) shortness is the dominant trait
(c) tallness is the recessive trait
(d) height of the plant is not governed by gene T or t
A trait in an organism is influenced by:
(a) paternal DNA only
(b) maternal DNA only
(c) both maternal and paternal DNA
(d) neither by paternal nor by maternal DNA
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