All practice questions

Match each noble gas listed on the left with its corresponding primary industrial application or physical property on the right.

In humans, Duchenne muscular dystrophy is inherited as an X-linked recessive disorder ($X^d$), while the normal allele is dominant ($X^D$). A phenotypically normal woman seeks genetic counseling. Her maternal grandfather had Duchenne muscular dystrophy, whereas her maternal grandmother was homozygous normal. Her father is phenotypically normal. If this woman marries a phenotypically normal man, what is the probability (expressed as a percentage) that their first male child will be affected by the disorder?

In an ecosystem, energy is lost as heat at each progressive trophic level according to the laws of thermodynamics. Which of the following ecological pyramids is ALWAYS upright in shape across all natural ecosystems?

Immunological serological tests demonstrate high precipitin cross-reactivity when human antibodies are mixed with chimpanzee serum proteins, indicating close structural homology resulting from a recent common evolutionary ancestor. Is this statement True or False?

Which of the following characteristics is a defining feature of discontinuous variation in a biological population?

In maize (*Zea mays*), purple endosperm color ($P$) is dominant over yellow endosperm color ($p$), and starchy kernel texture ($S$) is dominant over waxy kernel texture ($s$). A plant heterozygous for both traits ($PpSs$) is allowed to self-pollinate, producing 480 kernels in the $F_2$ generation. How many of these kernels are expected to display the purple endosperm and waxy kernel texture phenotype?

Match each respiratory process with its corresponding characteristic end-products.

Match each ecological measuring instrument in the left column with the corresponding abiotic factor it measures in the right column.

In humans, red-green color blindness is an X-linked recessive trait ($X^c$), whereas normal vision is controlled by the dominant allele ($X^C$). Albinism is an autosomal recessive disorder ($a$), whereas normal skin pigmentation is controlled by the dominant allele ($A$). A woman with normal vision and normal skin pigmentation, whose father was both color-blind and albino, marries a man with normal vision who is a carrier for albinism. If this couple produces a male child (son), what is the percentage probability that the son will be both color-blind and albino?

A study conducted on a human population recorded two phenotypic traits: resting systolic blood pressure (Trait I) and the presence or absence of the Rhesus D antigen on red blood cells (Trait II). Trait I produced a smooth, bell-shaped frequency distribution curve across a continuous gradient of values, whereas Trait II resulted in two distinct, non-overlapping categories with no intermediate forms. Which of the following correctly explains the genetic mechanism and environmental susceptibility responsible for these observed patterns of variation?

Match each core Lamarckian evolutionary postulate or related historical criticism on the left with its accurate biological mechanism or empirical evaluation on the right.

A single virion contains both DNA and RNA concurrently enclosed within its protein capsid to enable independent protein synthesis outside a living host cell.

A waterlogged agricultural field experiences prolonged anaerobic conditions following excessive irrigation. Laboratory analysis of the soil reveals a marked decline in soil nitrate ($NO_3^-$) concentration accompanied by a corresponding release of dinitrogen gas ($N_2$) into the atmosphere. Which microbial process and bacterial genus are primarily responsible for this nitrogen transformation?

During the electrolysis of concentrated hydrochloric acid ($HCl_{(aq)}$) using inert graphite electrodes, a gaseous product $X$ is evolved at the anode while gas $Y$ is evolved at the cathode. Which option correctly identifies gas $X$, gas $Y$, and the primary factor responsible for the preferential discharge that yields gas $X$?

In classic Mendelian genetics, a testcross is carried out by mating an organism exhibiting a dominant phenotype with an individual that is homozygous dominant for the trait in question.

Helium is used in deep-sea diving gas mixtures (heliox) to prevent decompression sickness and in meteorological balloons to provide lift. Which set of properties makes helium suitable for both of these applications?

Unicellular organisms such as *Chlamydomonas* require light to synthesize organic compounds. Which specialized subcellular organelle functions as a light-sensitive region that enables the organism to perceive light and exhibit positive phototaxis?

A comparative biological study analyzes three distinct fungal organisms: unicellular yeast (*Saccharomyces*), filamentous bread mould (*Rhizopus*), and a macrofungal mushroom (*Agaricus*). Which of the following statements correctly identifies a fundamental structural and metabolic feature common to all three organisms that distinguishes Kingdom Fungi from plants and bacteria?

Analogous structures, such as the camera-type eye of an octopus and the eye of a mammal, share a common embryonic origin and basic structural arrangement inherited from a shared recent ancestor.

An ecologist compared two disturbed ecosystems: Site X, an abandoned agricultural field where topsoil and organic seed banks remained intact, and Site Y, a newly exposed volcanic basalt ledge devoid of organic soil. Which of the following observations correctly contrasts the ecological succession dynamics between Site X and Site Y?