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प्रश्न
Explain the mode of sex determination in honeybees.
उत्तर
In hymenopteran insects such as honeybees, ants and wasps, a mechanism of sex determination called haplodiploidy mechanism of sex determination is common. In this system, the sex of the offspring is determined by the number of sets of chromosomes it receives. Fertilized eggs develop into females (Queen or Worker) and unfertilized eggs develop into males (drones) by parthenogenesis. It means that the males have half the number of chromosomes (haploid) and the females have double the number (diploid), hence the name haplodiploid for this system of sex determination.
This mode of sex determination facilitates the evolution of sociality in which only one diploid female becomes a queen and lays the eggs for the colony. All other females which are diploid having developed from fertilized eggs help to raise the queen’s eggs and so contribute to the queen’s reproductive success and indirectly to their own, a phenomenon known as Kin Selection. The queen constructs their social environment by releasing a hormone that suppresses fertility of the workers.
संबंधित प्रश्न
Differentiate between male and female heterogamety
Which of the two, sperm or ovum, decides the sex of the child?
In a human, how many chromosmes are present in a sperm in the testes?
In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosomes is/are :
(i) large chromosome
(ii) small chromosome
(iii) Y chromosome
(iv) X chromosome
In which livings, female decides the sex? Give two examples.
Complete the following sentence with appropriate word:
___________ chromosomes do not take part in sex determination.
How drones are produced in honey bees?
XO type of sex determination and XY type of sex determination are examples of ____________.
There are five daughters and no son in a family. It is because
Match the items of Column I with Column II:
| Column I | Column II | ||
| i. | XX-XO method of Sex Determination | a. | Turner syndrome |
| ii. | XX-XY method of Sex Determination | b. | Female heterog ametic |
| iii. | karyotype-45 | c. | Grasshopper |
| iv. | ZW-ZZ method of Sex Determination | d. | Female homogametic |
Sex is determined in human beings ______.
In XO type of sex determination ______.
Which of the following determines the sex of a child?
Select the incorrect statement
Select the statements that describe characteristics of genes
- genes are specific sequence of bases in a DNA molecule
- a gene does not code for proteins
- in individuals of a given species, a specific gene is located on a particular chromosome
- each chromosome has only one gene
The belief that the mother is completely responsible for the sex of the child is wrong because the child
The chromosomal constitution of a human female can be written as ______
All human chromosomes ate not paired. Most human chromosomes have a maternal and a paternal copy, and we have 22 such pairs. But one pair called the sex chromosomes, is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes. But men have a mismatched pair in which one is normal sized while the other is a short one.
(a) In humans, how many chromosomes are present in a Zygote and in each gamete?
(b) A few reptiles rely entirely on environmental cues for sex determination. Comment.
(c) "The sex of a child is a matter of chance and none of the parents are considered to be responsible for it." Justify it through flow chart only.
OR
(c) Why do all the gametes formed in human females have an X chromosome?
What is sex determination? Explain the mechanism of sex determination in the case of birds.
