Biology Test 27

Amylose is a helical polymer made of α–D-glucose units, bound to each other through α (1 → 4) glycosidic bonds.

The amino acids are the building blocks of the proteins. They are also the end‑products of the digestion of proteins.

Total number of carbons in β-D fructofuranose is 6.

Glycine is the smallest of the 20 amino acids commonly found in proteins. It is a colourless, sweet-tasting crystalline solid

Because increase in percentage of fauna (animals) will increase the amount CO₂ in atmosphere and the decrease in flora (plants) will decrease the utilization of CO₂ via photosynthesis thereby increasing the percentage of CO₂ in atmosphere.

Herbicides (e.g., 2, 4–D, 2, 4, 5–T), insecticides (e.g. DDT, aldrin, BHC) and rodenticides causes water pollution.

Silicosis is caused by inhalation of dust containing free silica or silicon dioxide especially by workers engaged in mining, pottery, ceramic industry, sand blasting, building and construction industries.

PAN prevents photolysis of water in photosynthesis or hill reaction.

• Intercostal muscles are several groups of muscles that run between the ribs, and help form and move the chest wall.
• The intercostal muscles are mainly involved in the mechanical aspect of breathing.
• These muscles help expand and shrink the size of the chest cavity to facilitate breathing.
• Femur, also called thighbone, upper bone of the leg or hind leg. It is the longest bone of the body.
• The head forms a ball-and-socket joint with the hip, being held in place by a ligament within the socket and by strong surrounding ligaments. 
• The radius and ulna are the bones of the forearm. The forearm is the region of the upper limb that extends from the elbow to the wrist.
• The radius bone supports the lateral thumb side of the forearm and the ulna bone supports the medial little finger side.

A muscle fibre contracts only once it is stimulated by a single nerve impulse or electric shock of adequate strength. This single isolated contraction of muscle fibre is called muscle twitch. Immediately after the brief twitch, the muscle fibre relaxes. But if a muscle fibre is stimulated by a rapid succession of many nerve impulses or electric shock, it remains in a state of sustained contraction so long as the stimulation continues. Such a continued state of contraction is tetanus. Much higher tension is developed in tetanus than in an isolated twitch.

In birds, the fore limbs are modified to form wings.

During strenous exercise, the muscle does not get sufficient oxygen to meet its energy needs immediately. So, it contracts anaerobically and accumulates lactic acid. During recovery, the oxygen consumption of the muscle far exceeds than in the resting state. The extra oxygen consumed during recovery is called oxygen debt of the muscle.

• Asexual reproduction is a type of reproduction by which offspring arise from a single organism, and inherit the genes of that parent only.
• It does not involve the fusion of gametes, and almost never changes the number of chromosomes.
• Advantages of asexual reproduction are-

• It produces two offsprings which are the exact copies of the parents.
• A large number of individuals can be produced in a very small time.
• Plants that grow vegetatively need less attention at early stages then the plants grown by seeds.
• Many seedless varieties like grapes, pineapple, Dahlia, bananas etc grow only through the vegetative method.

Asexual reproduction involves a single parent i.e. uniparental. It results in offspring that are genetically identical to each other and to the parent
Characteristics:

• It does not involve the fusion of gametes.
• Almost never changes the number of chromosomes.
• Interchange of genes between individuals are more limited
• Rapid population growth. This is especially useful for species whose survival strategy is to reproduce very fast.

Syngamy (fertilisation), a process of sexual reproduction, occurs between the male and female gametes.

Syngamy may occur either externally, outside the body of organisms or internally, inside the body. This process leads to formation of a specialized cell called zygote.

Asexual reproduction is a mode of reproduction in which the new offspring arise from a single parent. The offsprings are identical to each other, both physically as well as genetically. They are the exact copies of their parent cell. Thus, they are Clones

Features of Asexual Reproduction:

• genetically similar offsprings i.e. limited variation 
• Involvement of the single parent
• No gamete formation or fertilization
• The whole process takes place in a small period of time
• Rapid multiplication and growth happens