Typhoid fever, also known as typhoid, is a common worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella typhi, serotype Typhi. The bacteria which causes typhoid fever may be spread through poor hygiene habits and public sanitation conditions, and sometimes also by flying insects feeding on feces. A person may become an asymptomatic carrier of typhoid fever, suffering no symptoms, but capable of infecting others.

Correct Option: B

Typhoid fever, also known as typhoid, is a common worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella typhi, serotype Typhi. The bacteria which causes typhoid fever may be spread through poor hygiene habits and public sanitation conditions, and sometimes also by flying insects feeding on feces. A person may become an asymptomatic carrier of typhoid fever, suffering no symptoms, but capable of infecting others.

Human skin colour is primarily due to the presence of melanin in the skin. Skin colour ranges from almost black to white with a pinkish tinge due to blood vessels underneath. Variation in natural skin colour is mainly due to genetics, although the evolutionary causes are not completely certain. Melanin is produced by cells called melanocytes in a process called melanogenesis. Melanin is triggered by an enzyme called tyrosinase, which creates the color of skin, eyes, and hair shades. Melanin controls the amount of ultraviolet (UV) radiation from the sun that penetrates the skin by absorption. While UV radiation can assist in the production of vitamin D, excessive exposure to UV can damage health.

Correct Option: D

Human skin colour is primarily due to the presence of melanin in the skin. Skin colour ranges from almost black to white with a pinkish tinge due to blood vessels underneath. Variation in natural skin colour is mainly due to genetics, although the evolutionary causes are not completely certain. Melanin is produced by cells called melanocytes in a process called melanogenesis. Melanin is triggered by an enzyme called tyrosinase, which creates the color of skin, eyes, and hair shades. Melanin controls the amount of ultraviolet (UV) radiation from the sun that penetrates the skin by absorption. While UV radiation can assist in the production of vitamin D, excessive exposure to UV can damage health.

The spiny dogfish shark (Squalus acanthias) is the most common shark and travels in schools. They are called dogfish because they travel and hunt in packs. They also migrate in schools, following cool waters. The spiny dogfish shark is found worldwide in temperate and subarctic waters, in the temperate and subarctic latitudes of the North Atlantic and North Pacific oceans. These sharks have even been found in the Black sea and Mediterranean sea.

Correct Option: C

The spiny dogfish shark (Squalus acanthias) is the most common shark and travels in schools. They are called dogfish because they travel and hunt in packs. They also migrate in schools, following cool waters. The spiny dogfish shark is found worldwide in temperate and subarctic waters, in the temperate and subarctic latitudes of the North Atlantic and North Pacific oceans. These sharks have even been found in the Black sea and Mediterranean sea.

When it comes to greenhouse gases many of us think first of CO₂. But a large proportion of global greenhouse gas emissions are actually other gases, such as N₂O (nitrous oxide) and CH₄ (methane). The emission of methane and nitrous oxide is largely the result of agricultural activities; nitrous oxide from fertilisers and methane mostly from cows. In peat pasture areas these emissions are particularly prevalent.

Correct Option: D

When it comes to greenhouse gases many of us think first of CO₂. But a large proportion of global greenhouse gas emissions are actually other gases, such as N₂O (nitrous oxide) and CH₄ (methane). The emission of methane and nitrous oxide is largely the result of agricultural activities; nitrous oxide from fertilisers and methane mostly from cows. In peat pasture areas these emissions are particularly prevalent.

Genetically, modified foods (GM foods) are foods derived from genetically modified organisms (GMOs), such as genetically modified crops or genetically modified fish. GMOs have had specific changes introduced into their DNA by genetic engineering techniques. These techniques are much more precise than mutagenesis (mutation breeding) where an organism is exposed to radiation or chemicals to create a non-specific but stable change. Other techniques by which humans modify food organisms include selective breeding; plant breeding, and animal breeding, and somaclonal variation.

Correct Option: B

Genetically, modified foods (GM foods) are foods derived from genetically modified organisms (GMOs), such as genetically modified crops or genetically modified fish. GMOs have had specific changes introduced into their DNA by genetic engineering techniques. These techniques are much more precise than mutagenesis (mutation breeding) where an organism is exposed to radiation or chemicals to create a non-specific but stable change. Other techniques by which humans modify food organisms include selective breeding; plant breeding, and animal breeding, and somaclonal variation.