The correct option is (A) : Down Syndrome = 21st Chromosome
Trisomy 21, sometimes referred to as Down syndrome (DS or DNS), is a genetic disease brought on by the presence of all or a portion of a third copy of chromosome 21. Physical growth delays, mild to severe intellectual handicaps, and distinctive facial traits are frequently connected with it. A young adult with Down syndrome has an average IQ of 50, which is comparable to an 8- or 9-year-old child's mental capacity, but this can vary greatly. Genetically, the afflicted person's parents are often unaffected. The likelihood rises from less than 0.1% for women under 20 to 3% for those over 45. There is no known behavioral activity or environmental element that alters the probability of the extra chromosome occurring; it is thought to happen randomly.
List I | List II | ||
---|---|---|---|
A | Two or more alternative forms of a gene | I | Back cross |
B | Cross of F1 progeny with homozygous recessive parent | II | Ploidy |
C | Cross of F progeny with any of the parents | III | Allele |
D | Number of chromosome sets in plant | IV | Test cross |
Structural organization in animals refers to the different levels of organization within their body, from the smallest unit of life to the entire organism.
At the cellular level, animals are composed of various types of cells that perform specific functions. These cells are organized into tissues, which are groups of similar cells that work together to perform a specific function. Different tissues then combine to form organs, such as the heart, lungs, and liver, which have specific functions within the body.
Multiple organs that work together towards a common goal make up an organ system, such as the respiratory or digestive system. Finally, all of the organ systems work together to form the entire organism.
The organization of an animal's body is critical to its survival and adaptation to its environment. Each level of organization is complex and requires a high degree of coordination and communication among cells, tissues, organs, and organ systems. The study of structural organization is important in understanding how animals function and how they adapt to their environment.