Biology Test - 6

Sacred groves are tracts of forests conserved by people due to religions, cultural beliefs that emphasize protection of nature. Khasi hills, Meghalaya is one such area.
Threatened animals, taken out from natural habitats are given special care at a special setting- Ex-situ conservation.
Zoological park is one such way of conservation.
Nile perch(fish) introduced in lake Victoria, Africa-led to extinction of more than 200 species of native, cichlid fish. So, Nile perch is example of Alien species invasion. Amazon forest covering more than 14% of earth's land surface, release large amount of O2.

Bacillus thuringiensis (Bt) strains have been utilized to create genetically modified crops, known as bio-insecticidal plants. These plants are engineered to produce insecticidal proteins derived from Bt, such as Cry proteins, which are toxic to certain insect pests. By incorporating Bt genes into crops like cotton, corn, and soybeans, these plants become resistant to specific insect pests, reducing the need for chemical insecticides and promoting environmentally friendly pest control strategies.

One of the special characters of Coelenterata only is the occurrence of Nematocysts.

Coelenterates are acoelomate. They have a one-hole that functions as the mouth and anus. The hole is enclosed by tentacles. The tentacles consist of specific types of cells known as nematocysts are located in Coelenterata only. These cells are used for food catching, defensive and offensive purposes. And also nematocysts cells serve to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs.

Cotton plants have been genetically modified to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt), specifically the CryAc and CryAb proteins. These proteins are toxic to cotton bollworms (Helicoverpa armigera), a common pest that damages cotton crops. The introduction of these genes into cotton confers resistance to bollworm infestation, reducing the need for chemical insecticides and promoting more sustainable agriculture.

The Bt toxin is used for killing nematodes in crop plants. But, it is non-toxic to humans due to conversion of pro Bt-toxin to Bt-toxin takes place in highly alkaline conditions. Bt toxins are used to kill insects but for humans, it is non-toxic because it behaves as a dietary protein. These breakdown very rapidly due to high acidic conditions in the human stomach and are harmless. As human stomach digests the concerned protein, therefore, it is not toxic to humans.

These fibres are cylindrical in shape is NOT the characteristic feature of Smooth Muscle Fibres.

Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs, such as the intestines, uterus and stomach. These fibres are spindle-shaped and are pointed at both ends.

They bear a single nucleus which is central. These are involuntary in nature and are also found in the tracts of the urinary, respiratory and reproductive systems. These muscles also play an important role in the ducts of exocrine glands.

Insects have compound eyes.

Insects like bees and mosquito's eyes are different from human eyes. Bees and mosquitos can see different direction at the same time because their eye has so many tiny lenses. The particular organs of each animal get evolved according to their need and the surrounding environment. They adapt themselves according to their environment, their movement, and their way to feed themselves.

Mosquitos and insects need to fly in the open air and catch their prey so they need to have a vision in different directions at the same time.

Genes are the units of heredity and are the instructions that make up the body’s blueprint. They code for the proteins that determine virtually all of a person's characteristics.

Humans have an estimated 35,000 genes. Most genes come in pairs and are made of strands of genetic material called deoxyribonucleic acid, or DNA.

Genetic disorders are caused by one or more changes, or mutations, in the instruction code of a particular gene(s), preventing the gene(s) from functioning properly.

• The study of human genetics is the study of human variation that is carried in the genes.
• The physical location of a gene is its locus. Different versions of genes are called alleles. For example, an eye color gene may have a blue allele and a brown allele.
• Genes are organized in structures called chromosomes.

The water follows two pathways apoplast and symplast. 

In the apoplast pathway, water is transported from root hair to xylem through the cell wall of intervening cells.

In symplastic pathway, the movement of water is in between the cytoplasm and the vacuoles through the plasma membranes and plasmodesmata and beyond the cortex of plant cells. The pathway is slower when compared to the apoplastic pathway.

In both the pathways, the route followed is from root hair to cortex to endodermis and pericycle, then to protoxylem and finally to metaxylem.

Emphysema gradually damages the air sacs (alveoli) in our lungs, making us progressively more short of breath. Emphysema is one of several diseases known collectively as chronic obstructive pulmonary disease (COPD). Smoking is the leading cause of emphysema.

Our lungs' alveoli are clustered like bunches of grapes. In emphysema, the inner walls of the air sacs weaken and eventually rupture creating one larger air space instead of many small ones. This reduces the surface area of the lungs and, in turn, the amount of oxygen that reaches our bloodstream.

When we exhale, the damaged alveoli don't work properly and old air becomes trapped, leaving no room for fresh, oxygen-rich air to enter. Treatment may slow the progression of emphysema, but it can't reverse the damage.