Punjab Biology 2021 Paper 2 — Solved MCQs

Question 1

The central station of metabolism and metabolic clearing house of the body is:

Accepted Answer

A. Liver — The liver is often referred to as the central station of metabolism because it plays a crucial role in various metabolic processes. It metabolizes nutrients from the digestive system, regulates blood glucose levels by storing or releasing glycogen, synthesizes proteins, processes fats, detoxifies harmful substances, and produces bile for fat digestion.

Question 2

Urine leaves the body through:

Accepted Answer

D. Urethra — The urethra is the tube that carries urine from the urinary bladder to the outside of the body during urination. In males, it also serves as the passage for semen during ejaculation.

Question 3

Which of these are bone forming cells?

Accepted Answer

A. Osteoblasts — Osteoblasts are bone-forming cells responsible for synthesizing and secreting the matrix of bone tissue. They play a crucial role in bone formation during growth and repair processes by depositing minerals, primarily calcium and phosphate, onto the bone matrix.

Question 4

Which one is needed to break the link between myosin bridge and actin?

Accepted Answer

B. ATP — ATP is the primary energy currency of cells and is required for various cellular processes, including muscle contraction. ATP binds to myosin heads, providing the energy needed for the cross-bridge cycle to occur. When ATP is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate (Pi), it provides the energy required for the myosin head to detach from actin, allowing muscle relaxation to occur.

Question 5

Excess thyroxine produces a condition called:

Accepted Answer

C. Grave's disease — Grave's disease is an autoimmune disorder that leads to hyperthyroidism, a condition characterized by excessive production of thyroid hormones, including thyroxine. Symptoms of Grave's disease can include weight loss, rapid heartbeat, tremors, sweating, and protruding eyes (exophthalmos). Excess thyroxine is a hallmark feature of Grave's disease.

Question 6

Placental lactogen in human females is secreted by:

Accepted Answer

D. Placenta — The placenta, a temporary organ that develops during pregnancy, is responsible for supplying oxygen and nutrients to the fetus and removing waste products. It also produces several hormones essential for maintaining pregnancy, including placental lactogen.

Question 7

Notochord is one of the few prominent structures seen in the embryo of:

Accepted Answer

D. 18 hours — In chick embryo of about 18 hours, notochord is one of the few prominent structural features.

Question 8

Grey vegetal cytoplasm of ascidian egg gives rise to:

Accepted Answer

C. Gut — The fertilized egg of an ascidian contains cytoplasm of five different colours that is segregated into different blastomeres.1. Clear cytoplasm: It produces larval epidermis.2. Yellow cytoplasm: It gives rise to muscle cells.3. Gray vegetal cytoplasm: It gives rise to gut.4. Grey equatorial cytoplasm: It produces notochord and neural tube.

Question 9

TTGACA binding site in prokaryotes is called:

Accepted Answer

B. -35 sequence — This sequence is located about 35 base pairs upstream of the transcription start site and contains the TTGACA sequence, which is recognized by the sigma subunit of RNA polymerase during transcription initiation. It plays a crucial role in positioning RNA polymerase and initiating transcription.

Question 10

The paired chromosomes start to separate during:

Accepted Answer

B. Diplotene — The paired chromosomes repel each other and begin to separate during diplotene. Separation however, is not complete, because homologous chromosomes remain united by their point of interchange (chiasmata). Each bivalent has at least one such point, the chromatids otherwise are separated.

Question 11

Individuals having 45 chromosomes with one missing "X" chromosome are affected by:

Accepted Answer

C. Turner's syndrome — Turner's syndrome is a genetic condition that affects females and is characterized by the complete or partial absence of one X chromosome. Instead of the usual 46 chromosomes, individuals with Turner's syndrome have only 45 chromosomes, with one missing X chromosome.

Question 12

MN blood type is an example of:

Accepted Answer

A. Codominance — In codominance, both alleles in a heterozygote are fully expressed. In the case of MN blood type, codominance means that both M and N alleles are expressed equally, resulting in individuals with both M and N antigens on their red blood cells.

Question 13

Plasmids were discovered while studying the sex life of:

Accepted Answer

A. E.Coli — Plasmids were discovered by investigators studying the sex life of the intestinal bacterium Escherichia coli.

Question 14

A respiratory protein found in all aerobic species is:

Accepted Answer

C. Cytochrome' c' — For instance, cytochrome c, a respiratory protein is found in all aerobic species.

Question 15

The actual location of an organism is called:

Accepted Answer

B. Habitat — Habitat refers to the specific place or type of environment where an organism lives. It encompasses both biotic (living) and abiotic (non-living) factors, such as the type of soil, climate, vegetation, and other organisms present in the area. For example, a habitat could be a forest, a pond, a desert, or even a human-made environment like a city.

Question 16

The coniferous forests located at high altitudes are called:

Accepted Answer

A. Alpine — Alpine forests are found in mountainous regions at high altitudes, typically above the tree line where temperatures are cooler and conditions are harsher. These forests are characterized by coniferous trees adapted to cold temperatures and rocky terrain. Alpine ecosystems are often diverse and can include a variety of plant and animal species adapted to the challenging conditions of high elevations.

Question 17

Which of these is a green house gas?

Accepted Answer

D. Carbon dioxide — Carbon dioxide is the primary greenhouse gas emitted through human activities such as burning fossil fuels, deforestation, and industrial processes. It's the most significant driver of global warming and climate change, trapping heat in the Earth's atmosphere.

Punjab Biology 2021 Paper 2 — Solved Past Paper with Answers

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