Find the 12th Class Fsc Part 2 Short Questions Online Preparation Biology

Question # 1

Define Transgenic Plants.Give its two uses.

Ans 1: Plants having foreign genes incorporated into their cells are known as transgenic plants.Two uses of transgenic plant are:
Ans 2: i) A weed called mouse-eared cress has been engineered to produce a biodegradable plastic in cell grannules.
ii) Plants are being engineered to produce human hormones,clotting factors and antibodies in their seeds.

Question # 2

What are metabolic defects and give two example?

Ans 1: Bones are malformed and one organ or its part is missing or it may be repeated.

Question # 3

What are the events of zygotene of prophase -I of meiosis?

Ans 1: First essential phenomenon of meiosis i.e, pairing of homologous chromosomes called synapsis starts. Each paired but not fused,complex structure is called bivalent or tetrad.

Question # 4

Define fruit.

Ans 1: Ripened ovary is called fruit. After the fertilization the cells of ovary wall starts to divide and it develops into complete fruit.

Question # 5

Differentitae between reflex arc and reflex action.

Ans 1: Reflex arc The path followed by the nerve impulse during the reflex action is called reflex arc.
Ans 2: Reflex Action Involuntary actions are called reflex action.This action is performed without the involvement of brain.

Question # 6

Explain genic system for determination of sex.

Ans 1: Many species of eukaryotic micro-organisms like yeast do not have sex chromosomes.These depend on genic system for determination of sex.In this system the sexes are specified by simple allelic differences at small number of gene loci.

Question # 7

Differentiate between parthenocarpy and apomixes.

Ans 1: Apomixes: In apomixes a diploid cell either from the nucellus or megaspore develops into a functional embryo in the absence of a male gamete.The rest of the ovule develops into seed and ovary into fruit.
Ans 2: Parthenocarpy: Formation of fruit without fertilization is called parthenocarpy. For example seedless grapes and banana.

Question # 8

Why ammonia is more toxic than other nitrogenous wastes?

Ans 1: Ammonia is very toxic and dissolve quickly in body fluids,Thus it must be kept in low concentration in the body.To maintain low concentration below that of body requires, large volume of water is used to eliminate it as urine.

Question # 9

What are Okazaki fragments? Also give their length.

Ans 1: During replication of DNA,one of its strands is discontinuously synthesized in the form of fragments called Okazaki fragments.Its length in eukaryotes is 100 to 200 nucleotides while in prokaryotes it is 1000 to 2000 nucleotides.

Question # 10

What is translation? Or Define translation.

Ans 1: Synthesis of protein from the mRNA is called translation.It is second step of central dogma.

Question # 11

Define phenylketonuria. OR What is phenylketonuria?

Ans 1: In phenylketonuria,phenylalanine is not degraded because of defective enzyme phenylalanine hydroxylase. Phenylalanine consequently accumulates in the cells leading to mental retardation,as the brain cells fails to develop in infancy.This disorder is due to point mutation.

Question # 12

Name the salt tolerant plants and give its role in future.

Ans 1: Arabidopsis is salt tolerant plant.The cultivation of this plant at saline soil will reclaim the soil conditions.The acrage of the crop in a field will be increased in this way.

Question # 13

What is average rainfall in temperate deciduous forests?

Ans 1: The average rain fall in temperate deciduous forest is 750mm to 150mm/annum.

Question # 14

What is metanephridium?

Ans 1: It is the excretory organ of earthworm and other annelids.In each segment of the body metanephridium is present which individually collects the wastes and then remove them.

Question # 15

Compare between epistasis and poleiotropy.

Ans 1: Epistasis: When an effect caused by a gene pair on one locus interferes with or hides the effect caused by another gene or gene pair at another locus,it is called epistasis.
Ans 2: Poleiotropy: When a single gene affects two of more traits,the phenomenon is called pleiotropy.

Question # 16

Discuss the role of two hormones produced by gut.

Ans 1: Gastrin produced from mucosa of pyloric region of stomach. It stimulates the production of gastric juice.
Ans 2: secretin produced from intestinal mucosa and it stimulates the production of pancreatic juice.

Question # 17

Define Succession.Name its types.

Ans 1: Succession is a sequence of changes in the community structure of an ecosystem over a period of time.In each case succession is initiated by a few hardy invaders called pioneers ant ends with a diverse and relatively stable climax community.e.g succession start on a bare rock in known as xerosere.
Ans 2: i) Primary succession ii) Secondary succession.

Question # 18

Give the role of oxytocin.

Ans 1: Oxytocin of ovum from the ovary is called ovulation

Question # 19

Define phototactic movement and photonastic movement.

Ans 1: Phototactic Movement: is a types of tactic movement in which movement occur in response to light stimulus. Photonastic Movements:that in which photoperiod is critical in opening and closing of flowers.

Question # 20

How sex is determined in yeast?

Ans 1: Sex determination in yeast depends upon genic system.In this system the sexes are determined by simple allelic difference at a small number of gene loci e.g,a and a are the two mating types or sexes of yeast controlled by MAT a and MAT.a alleles respectively.