Punjab Biology 2015 Paper 1 — Solved MCQs

Question 1

The plants that have adaptation of small and thick leaves to reduce water loss are called

Accepted Answer

C. Xerophytes — Xerophytes are a group of plants that are adapted to survive in arid regions like desert and snow-covered areas. Xerophytes have stomata with microscopic openings and elongated leaves that store large amounts of water. Sometimes even their stems store water. They have deep-spreading roots that search for water.

Question 2

The excretory product that requires minimum water for its elimination is

Accepted Answer

B. Uric acid — Only 1ml water is required to eliminate 1g of nitrogen in the form of uric acid. Therefore, the reptiles and birds that inhabit arid environments, excrete uric acid as an excretory product.

Question 3

Muscle fatigue is caused by

Accepted Answer

D. Lactic acid — Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2. During intense exercise sustained to fatigue muscle pH decreases to about 6.4-6.6.

Question 4

Which of the following animals has hydrostatic skeleton

Accepted Answer

C. Sea anemone — Unlike sponges, which have skeletal structures made of spongin or spicules, sea anemones and jellyfish have no skeletal structure to support their soft tissues. For support, they fill the gastrovascular cavity with water and close the mouth tight, putting the water under pressure as in a balloon filled with water.

Question 5

Which of the hormones suppresses ovulation?

Accepted Answer

D. Progesterone — The main function of progesterone is to prepare the endometrium (lining of your uterus) for a fertilized egg to implant and grow. If a pregnancy doesn't occur, the endometrium sheds during your menstrual period. If conception occurs, progesterone increases to support the pregnancy. It also stops ovulation.

Question 6

Reproduction is very important to the survival of

Accepted Answer

A. Species — It is a biological process through which living organisms produce offspring similar to them. Reproduction ensures the continuity of various species on the Earth. In the absence of reproduction, the species will not be able to exist for a long time and may soon get extinct.

Question 7

External fertilization occurs in

Accepted Answer

B. Aquatic environment — External fertilization occurs in aquatic environments where male gametes can swim toward the female-gametes in water medium. Development is also external due to the constant/stable conditions of water (frogs, fish, etc.)

Question 8

In which developmental stage, germs layer are formed

Accepted Answer

D. Neurulation — Gastrulation occurs during week 3 of human development. The process of gastrulation generates the three primary germ layers ectoderm, endoderm, and mesoderm

Question 9

The sequence of nucleotides that determines the amino acid sequence of a protein is called

Accepted Answer

D. Genetic code — The nucleotide sequence of a gene, through the medium of mRNA, is translated into the amino acid sequence of a protein by rules that are known as the genetic code. This code was deciphered in the early 1960s.

Question 10

Mongolism is also known as

Accepted Answer

A. Down syndrome — Trisomy 21, the most frequent variant of Down syndrome (also known as mongolism), is a disease in which people have 47 chromosomes in each cell instead of 46.

Question 11

Bivalent or Tetrad are formed in

Accepted Answer

B. Zygotene — The formation of a bivalent occurs during the first division of meiosis (in the zygotene stage of meiotic prophase 1).

Question 12

Chances of genetic recombination are minimized due to

Accepted Answer

D. Gene linkage — Gene linkage also minimizes the chances of genetic recombination and variations among offspring.

Question 13

Which of the enzymes act as molecular scissors?

Accepted Answer

B. Restriction Endonuclease — Restriction enzymes are also called "molecular scissors" as they cleave DNA at or near specific recognition sequences known as restriction sites. These enzymes make one incision on each of the two strands of DNA and are also called restriction endonucleases.

Question 14

Who published an essay on " The principle of population"?

Accepted Answer

C. Malthus — Essay on the Principle of Population. The first, published anonymously in 1798, was so successful that Malthus soon elaborated on it under his real name.

Question 15

The study of a single population's relationship to the environment is called

Accepted Answer

A. Autecology — Autecology is the study of individual organisms. The approach originally focused on the adaptiveness of an organism׳s physiology to the environment but has since been expanded to include the study of the distribution and dynamics of populations.

Question 16

Which of the biomes has been increased in area by human activities.

Accepted Answer

D. Desert — The desert biome has increased in area due to human activities. While human activities are reducing the extent of many biomes, they are causing the spread of deserts, a process called desertification.

Question 17

Which of the following is a renewable resource

Accepted Answer

B. Land — A renewable resource is a resource of which there is an endless supply because it can be replenished. The sun, the wind, and geothermal heat are considered inexhaustible and therefore are examples of renewable resources. Water is also considered a renewable natural resource, as long as there is precipitation.

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