1 :- Chromosome : It is a Genetic material. It is present in Nucleus. The nucleoplasm contains certain thread-like elonigated structures known as chromosomes. The chromosomes appear only during cell division otherwise they occur in the form of chromatin granules. The chromatin granules or chromosomes fundamentally conisist of large molecules of deoxyribonucleic ACID (DNA) and many nucleoproteins.Humans have 23 pairs of chromosomes. Centromere :The chromosome has constricted region CALLED Centromere (primary canstriction). .This is the region, of the chromosomes that becomes attached to the mitotic spindle.The position of the centromere is constant for a GIVEN species, and forms a feature identification. The centromere consists of highly repetitive DNA (heterochromatin), with special proteins bound to it, forming a disc - shaped structure (kinetochore).______________________Answer 2 :- (I) ColeoptileIt is present in Monocot seeds. It is sheath protecting a young shoot tip in grass or cereal. (2) Cartilage It is found in body mainly in external ear, larynx, respiratory tract and other joints. It is a flexible connective tissue that protects the bone from rubbing against each other.______________________Answer 3 :- Binomial Nomenclature :- It is a biological naming system in which organisms are named in form of two terms as first term is genus and the second term indicates the species of the organism. Example such as Human which has biological name "Homo sapiens" . ×××××××××××××××××××××××××———————————————More to know :- Rules of Biological Nomenclature:- Names are written in italicized form.First letter of genus should be capital.First letter of species should be in lowercase.If SCIENTIFIC texts are handwritten, they should be underlined.About Centromere :- Types of chromosomes based on number of centromere. The vast majority of chromosomes have one centromere (Monocentric- chromosomes). But the number may be different in different chromosomes:Monocentric - with one centromereDicentric- with two centromeres, one n each, chromatid.Polycentric- with many centromeres.Holocentric- with INDISTINCT centromere, the microtubules attached along the length of the chromosome.Acentric*- chromosomes without centromere.[Note :- Also There are many Types of chromosomes based on position of centromere but it can be lengthy so it can't be explained .]