Biology: CUET Mock Test - 9 - CUET MCQ

The skull belongs to Homo erectus erectus, also known as Java man. Chin was absent whereas jaw prognathous. They were omnivorous. Cannibalism was also found.

PCR is used to amplify specific DNA sequences, allowing researchers to generate large quantities of a target gene.

PCR involves denaturation, annealing, and extension, but replication is not specifically one of the steps.

DNA polymerase extends the primers by adding nucleotides to form new DNA strands during the extension step of PCR.

In PCR, each cycle doubles the amount of the target DNA, leading to exponential amplification of the DNA segment.

PCR is widely used in genetic research, medical diagnostics, and forensic science for amplifying DNA samples.

Genetically engineered insulin is identical to the insulin produced by humans, making it safer and reducing allergic reactions compared to animal-derived insulin.

Escherichia coli is genetically engineered to produce human insulin by incorporating the human insulin gene into its genome.

The main challenge in recombinant DNA insulin production is getting the insulin chains to mature by creating disulfide bonds between them.

Insulin regulates blood sugar levels by helping cells absorb glucose, which is essential for managing diabetes.

Eli Lilly was the first company to produce human insulin using recombinant DNA technology in 1983.

(A) Correct: Energy decreases as you move up trophic levels due to inefficiency in energy transfer.
(B) Correct: Primary consumers are herbivores, and secondary consumers are carnivores, feeding on herbivores.
(C) Incorrect: The detritus food chain begins with dead organic matter, not producers.
(D) Correct: Energy captured by producers is transferred to consumers through various trophic levels.
(E) Incorrect: Trophic levels represent feeding levels, not positions in a food chain.

(A) Correct: Primary producers (plants) capture solar energy and convert it into chemical energy through photosynthesis.
(B) Incorrect: The lowest trophic level in an energy pyramid consists of producers, not consumers.
(C) Correct: In terrestrial ecosystems, the biomass pyramid is generally upright because producers have more biomass than consumers.
(D) Correct: In a grazing food chain, energy flows from producers (plants) to herbivores and then to carnivores.
(E) Incorrect: Phytoplankton are primary producers in aquatic ecosystems, not primary consumers.

(A) Correct: Species diversity generally decreases as we move away from the equator towards the poles.
(B) Correct: India is one of the top 12 countries, known as mega-diverse countries, with high species diversity.
(C) Correct: Ecological diversity refers to the variety of ecosystems such as forests, wetlands, deserts, and more.
(D) Incorrect: Species richness tends to increase with area, not decrease.
(E) Correct: Habitat loss and fragmentation are significant contributors to species loss.

(A) Correct: Habitat destruction and fragmentation disturb ecosystems, leading to species loss.
(B) Incorrect: Invasive alien species often disrupt local ecosystems and lead to the decline of native species.
(C) Correct: Over-exploitation occurs when resources are harvested unsustainably, endangering species.
(D) Correct: Ex situ conservation involves the protection of species outside their natural habitats, such as in zoos or botanical gardens.
(E) Correct: In situ conservation involves protecting species in their natural habitats, maintaining entire ecosystems.

Homo  erectus, also known as Java man used fire for hunting, protection, and cooking. It had complete erect posture and lived in caves. It used tools of bones and stones.

Homo erectus were known as the direct ancestors of humans. It had many similarities to modern man. Their face, skull structure, and posture were the same.

They had a cranial capacity of 650-800 c.c. They were the first human being like and had complete erect posture similar to them. They had the knowledge to create tools of stones to hunt.

Natural selection mainly leads to three selections. They are: Stabilizing selection, directional selection, and disruptive selection. Technical selection does not belong to natural selection. This classification is based on different organism-environmental relationship.

Mortality in babies is an example of stabilizing selection. It is all depended on the baby’s birth weight. The optimum birth weight is 7.3 pounds which favor this selection. Newborn infants with less than 5.5 pounds and more than 10 pounds have the highest mortality rate.

Directional selection is also known as progressive selection. This selection always operates in a changing environment. After this natural selection, mean value always changed.

The graph given belongs to directional selection as the graph shifts to one direction. The resistance of insects to DDT is an example of directional selection. A single mutation which occurred in a specific gene helped them to breakdown the toxin. It shows that it favored one extreme value.

In disruptive selection, most of the individuals get the periphery values at both ends of the curve given in the graph. The population gets divided into two different groups. Hence, they have two peaks which resemble a two-humped camel.

Limpets shell has a continuous pattern with color ranging from pure white to dark tan. They either attached to white gooseneck barnacles or to tan colored rocks. The light-colored limpets camouflaged with white barnacles while tanned limpets camouflaged on tan-colored rocks. But, the limpets with intermediate shell patterns were conspicuous and were preyed by predatory shorebirds.

Marine mollusca is also known as limpets. They are aquatic snails with a conical shaped shell with a muscular foot. They are members of the family Gastropoda. Their shell pattern shows disruptive selection.

In disruptive selection, the members of both extreme are selected. The average gets rejected. Most of the individuals get values other than the mean character value. The naturally selected members are shown by two peaks.

This graph indicates stabilizing selection. As we can see, the peak gets higher and narrower. In this selection, most of the individuals acquire mean character value.

Stabilizing selection operates in a constant environment. It favors the average or complex phenotype and eliminates the extreme values. The mean value never changes. Also, the peak gets higher and narrower.

Cistrons are the segments of the DNA helical structure which code for polypeptide chains. The structural gene in the transcription unit can be either monocistronic or polycistronic. The monocistronic genes are mostly present in eukaryotes.

The sequences of the genes which appear in the mature or processed RNA are called as exons. They are the coding sequences of the gene. These sequences are interrupted by introns. Introns are the intervening sequences which aren’t present in both the mature or the processed RNA.