Biology Test - 71

This was the Jurassic Period, 199.6 to 145.5 million years ago* — a 54-million-year chunk of the Mesozoic Era. Named for the Jura Mountains on the border between France and Switzerland, where rocks of this age were first studied, the Jurassic has become a household word with the success of the movie Jurassic Park.

The ancient Egyptians made a parchmentlike paper, also called papyrus, from the pith, or inner portion, of the stalk of the papyrus plant.

Co-dominance: A condition in which both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other. Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.

Human chromosomes are divided into 7 groups A, B, C, D, E, F and G depending upon their size and position of centromere. Group A chromosomes are chromosomes 1 to 3. These are largest chromosomes and are metacentric, centromere is in the center. Group B chromosomes include chromosomes 4 and 5. These are large and are submetacentric. Group C chromosomes include chromosomes 6 to 12 and X. These are medium in size and are submetacentric. Group D chromosomes include chromosomes 13 to 15. These are medium in size and are acrocentric, centromere is towards the one end of chromosome. Group E chromosomes include chromosomes 16 to 18. These are medium in size and are metacentric and submetacentric. Group F chromosomes include chromosomes 19 and 20. These are small in size and are metacentric. Group G chromosomes include chromosomes 21, 22 and Y. These are small in size and are acrocentric.

The major task of the ear is to detect, transmit and transduce sound. Another very important function of the ear is to maintain our sense of balance.

Human diploid cells have 46 chromosomes (the somatic number, 2n) and human haploid gametes (egg and sperm) have 23 chromosomes (n).

The average person has about 10,000 taste buds and they're replaced every 2 weeks or so. But as a person ages, some of those taste cells don't get replaced. An older person may only have 5,000 working taste buds. That's why certain foods may taste stronger to you than they do to adults.

Pulmonary compliance increases with increase in age is true for lungs.

Changes in lung compliance can indicate issues within the lungs. These generally cause, or are caused by, injuries, illnesses, or impairments. Increased compliance can be present where there is degeneration of lung tissue. Degenerative lung tissue diseases (eg emphysema) make it harder for the lungs to expand, and harder to exhale as there is less elastic recoil.

Contralateral loss of pain and temperature is due to injury to the lateral spinothalamic tract.

• Damage to lateral spinothalamic tract leads to loss of pain and temperature on the opposite side of the body below the level of lesion, since the neurons of this tract crosses to the opposite side in the spinal cord.
• Anterior spinothalamic tract carries crude touch and pressure sensations. Fasciculus gracilis and fasciculus cuneatus carries conscious proprioception, fine touch, stereognosis and vibration sensations.

Functional residual volume is after normal inspiration. Functional residual capacity (FRC), is the volume remaining in the lungs after a normal, passive exhalation. In a normal individual, this is about 3L. The FRC also represents the point of the breathing cycle where the lung tissue elastic recoil and chest wall outward expansion is balanced and equal.