Explanation

In Ascidian embryos, the grey crescent gives rise to the notochord. 

The gray crescent:

• In ascidian development, the gray crescent is a region of pigmented cytoplasm located at the posterior of the fertilized egg.
• It is important for determining the future location of the notochord and neural tube. 

Notochord formation:

• The cells derived from the gray crescent are specifically destined to form the notochord, a rod-like structure that provides structural support during development. 

Explanation

Apiculture is the practice of rearing and maintaining honeybees for the production of honey, beeswax, and other bee-related products. It involves beekeeping and managing bee colonies for commercial and agricultural purposes.

• The other options refer to different types of cultivation:

• Mori culture (A) – Cultivation of mulberry plants for silkworms.

• Sericulture (B) – Rearing of silkworms for silk production.

• Silviculture (D) – Cultivation of forests and trees

Explanation

Ecotones:

Ecotones are transitional areas between different ecosystems or biomes, where there's a change in species composition and abundance. 

Beta Diversity:

Beta diversity measures the difference in species composition between different habitats or communities, which is precisely what happens at an ecotone. 

Alpha Diversity:

Alpha diversity refers to the diversity within a single habitat or community. 

Gamma Diversity:

Gamma diversity refers to the total diversity across a region or landscape. 

Explanation

Gigantism and Dwarfism are diseases related to the growth hormone of the adenohypophysis.

Explanation

The Demoiselle crane is a migratory bird that visits Pakistan

Demoiselle Crane ( Anthropoides virgo):

This species breeds in central Eurasia, ranging from the Black Sea to Mongolia and northeast China. 

Migration:

Demoiselle cranes are migratory birds, and those from Asia, Mongolia, and China spend the winter in the Indian subcontinent, including Pakistan. 

Explanation

Global warming is primarily caused by the increasing levels of carbon dioxide (CO2) in the Earth's atmosphere, which traps heat and leads to a warming effect.

The main reason for this increase is human activities such as:

• Burning fossil fuels like coal, oil, and gas
• Deforestation and land-use changes

Explanation

The unit of rock that represents all rocks formed during the same geological time scale is a Series. 

Geochronologic Units:

The units of time in the geological time scale are called geochronologic units (e.g., eon, era, period, epoch)

Explanation

Explanation

Grass carp require running water for breeding.

This environment is crucial for the successful spawning and development of their eggs.

As it helps maintain oxygen levels and water quality.

Explanation

 It hibernates throughout the winter in the northwestern Himalayas

Currently, it only exists in Asia, mainly confined in the Himalayas of India, Bhutan, Nepal, China, and Pakistan.