The major causes for biodiversity decline are:
(i) Habitat loss, fragmentation, and destruction (affects about 73% of all species)
(ii) Pollution and pollutants (smog, pesticides, herbicides, oil slicks, GHGs)
(iii) Climate change
(iv) Introduction of alien/exotic, species.
(v) Over exploitation of resources (poaching, indiscriminate cutting of trees, overfishing, hunting, mining).
(vi) Intensive agriculture and aquacultural practices.
(vii) Hybridization between native and nonnative species and loss of native species
(viii) Natural disasters (Tsunami, forest fire, earthquake, volcanoes).
(ix) Industrialization, Urbanization, infrastructure development, Transport - Road and Shipping activity, communication towers, dam construction, unregulated tourism, and monoculture are a common area of specific threats.
(x) Co-extinction.

(i) The inheritance of a trait that is determined by a gene located on one of the sex chromosomes is called sex linked inheritance.
(ii) Genes present on the differential region of X or Y chromosomes are called sex linked genes. The genes present in the differential region of "X" chromosome are called X linked genes. The X-linked genes have no corresponding alleles in the Y chromosome.
(iii) The genes present in the differential region of Y chromosome are called Y- linked or holandric genes. The Y linked genes have no corresponding allele in X chromosome.
(iv) The Y linked genes inherit along with Y chromosome and they phenotypically express only in the male sex.
(v) Sex linked inherited traits are more common in males than females because, males are hemizygous and therefore express the trait when they inherit one mutant allele.
(vi) The X - linked and Y - linked genes in the differential region (non-homologus region) do not undergo pairing or crossing over during meiosis. The inheritance of X or Y linked genes is called sex-linked inheritance.
X linked Inheritance - Eg. Colour blindness
Y linked Inheritance - Eg. hypertrichosis 

The diagrammatic representation of position of genes and related distances between the adjacent genes is called gene mapping. 
Uses 
(i) Used to determine gene order.
(i) Identify the locus of a gene.
(i) Calculate the distance between genes.
(i) Useful in predicting results of dihybrid and trihybrid crosses.
(i) Allows the geneticists to understand the overall genetic complexity of particular organism.

Dicot Seed	Monocot Seed
Seed coat differentiated into outer hard testa, inner thin membranous tegmen.	Seed coat brownish membranous unilayer closely adhered to the grain
Two cotyledons, laterally attached to the embryonic axis	Embryo consists of one shield shaped cotyledon, the scutellum
The reserve food materials stored either in cotyledon or in endosperm	The reserve food materials stored in the endosperm.
Embryonic axis is differentiated into radicle and plumule but not protected by any sheath	Embryonic axis is differentiated into radicle and plumule Radicle is protected by Coleorhiza Plumule is protected by Coleoptile
Example - Cicer arientinum	Example - Oryza sativa

1. Avoid sex with unknown partner/multiple partner
2. Use condoms.
3. In case of doubt, consult a doctor for diagnosis and get complete treatment.

syngamy	fertilization
It is the fusion of two haploid gametes to form a diploid zygote	It is the act (or) process of rendering fertile zygote as the result of Fertilization

 

No.	Tundra Biome	Taiga Biomes
1.	This is almost treeless plain in the northern parts of Asia, Europe, and North America.	Taiga is a forest of coniferous trees such as spruce, fir and pine.
2.	Winters are long with little daylight, summers are short, with long daylight hours.	Summer temperature ranges from 10octo 21oPc.
3.	Because of the severe winters, many of the animals are migratory. For E g: the many shore birds and water fowl such as ducks and geese, nest in the Tundra during the summer and migrate south for the winter.	Important migratory herbivores include moose, elk, deer and reindeer. Moose and reindeer migrate to the Taiga for winter and to Tundra for summers.

1. Farmers need to be made aware about organic farming which does not require any kind of fertilizers and pesticides usage.
2. Crop rotation can be practiced by farmers which reduces the need for fertilizers and improves the fertility of the soil.
3. Ships and tankers that carry oil can be supervised earlier and ensured that they are not damaged in any way and through this oil will not be split in the ocean water.

Human Ovum
a - Vitelline membrane
b - Nucleus
c - Zona Pellucida
d - Corona radiata

(i) Mild tremors to convulsions.
(ii) Severe agitation and fits.
(iii) Depressed mood.
(iv) Anxiety.
(v) Nervousness.
(vi) Restlessness.
(vii) Irritability.
(viii) Insomnia.
(ix) Dryness of throat.