267294
In some viruses, RNA is present instead of DNA indicating that
1 their nucleic acid must combine with host DNA before replication.
2 they cannot replicate.
3 there is no hereditary information.
4 RNA can transfer heredity material.
Explanation:
(d) Viruses are defined as infectious nucleoproteins. A complete virus particle is called virion whose main function is to deliver its DNA or RNA gesnome into the host cell, so that genome can be expressed by the host cell. In a particular virus either DNA or RNA is genetic material, never both are present in a virus. Hence, viruses are:
(i) Double stranded DNA or ds DNA - Hepatitis B
(ii) Single stranded DNA or ss DNA - coliphage
(iii) Double stranded RNA or.ds RNA - Reo virus, wound Tumor virus
(iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)
NCERT Page-26 / N-20
Biological Classification
267295
T. O.Diener discovered a new infectious agent that was smaller than viruses and have the following characteristics.
(i) It causes potato spindle tuber disease.
(ii) It has free RNA.
(iii) Molecular weight of RNA is low.
Identify the infections agent.
1 Prions
2 Viroids
3 Lichens
4 Mycoplasma
Explanation:
(b) Viröids cause potato spindle tuber disease (PSTV), chrysanthemum stunt, citrus exocortis, cucumber pale fruit etc. They cause persistent infections, i.e., never recovered.
NCERT Page-27 / N-21
Biological Classification
267296
The symbiotic association between fungi and algae is called
1 lichen
2 mycorrhiza
3 rhizome
4 endomycorrhiza
Explanation:
(a) The symbiotic association of fungi and algae is called Lichen. In lichen, there are two components i.e., algal partner called phycobiont and fungal partner called mycobiont.
NCERT Page-27 / N-21
Biological Classification
267297
Lichens indicate $\text{S}{{\text{O}}_{2}}$ pollution because they
1 show association between algae and fungi.
2 grow faster thanothers.
3 are sensitive to $\text{S}{{\text{O}}_{2}}$.
4 flourish in $\text{S}{{\text{O}}_{2}}$ rich environment.
Explanation:
(c) Lichens are formed by symbiotic relationship between algae or cyanobacteria and fungi. Lichens typically grow in harsh environments most lichens, especially epiphytic fruticose species and those containing cyanobacteria, are sensitive to pollutants. Hence, they have been widely used as $\text{S}{{\text{O}}_{2}}$ pollution indicator organisms.
267294
In some viruses, RNA is present instead of DNA indicating that
1 their nucleic acid must combine with host DNA before replication.
2 they cannot replicate.
3 there is no hereditary information.
4 RNA can transfer heredity material.
Explanation:
(d) Viruses are defined as infectious nucleoproteins. A complete virus particle is called virion whose main function is to deliver its DNA or RNA gesnome into the host cell, so that genome can be expressed by the host cell. In a particular virus either DNA or RNA is genetic material, never both are present in a virus. Hence, viruses are:
(i) Double stranded DNA or ds DNA - Hepatitis B
(ii) Single stranded DNA or ss DNA - coliphage
(iii) Double stranded RNA or.ds RNA - Reo virus, wound Tumor virus
(iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)
NCERT Page-26 / N-20
Biological Classification
267295
T. O.Diener discovered a new infectious agent that was smaller than viruses and have the following characteristics.
(i) It causes potato spindle tuber disease.
(ii) It has free RNA.
(iii) Molecular weight of RNA is low.
Identify the infections agent.
1 Prions
2 Viroids
3 Lichens
4 Mycoplasma
Explanation:
(b) Viröids cause potato spindle tuber disease (PSTV), chrysanthemum stunt, citrus exocortis, cucumber pale fruit etc. They cause persistent infections, i.e., never recovered.
NCERT Page-27 / N-21
Biological Classification
267296
The symbiotic association between fungi and algae is called
1 lichen
2 mycorrhiza
3 rhizome
4 endomycorrhiza
Explanation:
(a) The symbiotic association of fungi and algae is called Lichen. In lichen, there are two components i.e., algal partner called phycobiont and fungal partner called mycobiont.
NCERT Page-27 / N-21
Biological Classification
267297
Lichens indicate $\text{S}{{\text{O}}_{2}}$ pollution because they
1 show association between algae and fungi.
2 grow faster thanothers.
3 are sensitive to $\text{S}{{\text{O}}_{2}}$.
4 flourish in $\text{S}{{\text{O}}_{2}}$ rich environment.
Explanation:
(c) Lichens are formed by symbiotic relationship between algae or cyanobacteria and fungi. Lichens typically grow in harsh environments most lichens, especially epiphytic fruticose species and those containing cyanobacteria, are sensitive to pollutants. Hence, they have been widely used as $\text{S}{{\text{O}}_{2}}$ pollution indicator organisms.
267294
In some viruses, RNA is present instead of DNA indicating that
1 their nucleic acid must combine with host DNA before replication.
2 they cannot replicate.
3 there is no hereditary information.
4 RNA can transfer heredity material.
Explanation:
(d) Viruses are defined as infectious nucleoproteins. A complete virus particle is called virion whose main function is to deliver its DNA or RNA gesnome into the host cell, so that genome can be expressed by the host cell. In a particular virus either DNA or RNA is genetic material, never both are present in a virus. Hence, viruses are:
(i) Double stranded DNA or ds DNA - Hepatitis B
(ii) Single stranded DNA or ss DNA - coliphage
(iii) Double stranded RNA or.ds RNA - Reo virus, wound Tumor virus
(iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)
NCERT Page-26 / N-20
Biological Classification
267295
T. O.Diener discovered a new infectious agent that was smaller than viruses and have the following characteristics.
(i) It causes potato spindle tuber disease.
(ii) It has free RNA.
(iii) Molecular weight of RNA is low.
Identify the infections agent.
1 Prions
2 Viroids
3 Lichens
4 Mycoplasma
Explanation:
(b) Viröids cause potato spindle tuber disease (PSTV), chrysanthemum stunt, citrus exocortis, cucumber pale fruit etc. They cause persistent infections, i.e., never recovered.
NCERT Page-27 / N-21
Biological Classification
267296
The symbiotic association between fungi and algae is called
1 lichen
2 mycorrhiza
3 rhizome
4 endomycorrhiza
Explanation:
(a) The symbiotic association of fungi and algae is called Lichen. In lichen, there are two components i.e., algal partner called phycobiont and fungal partner called mycobiont.
NCERT Page-27 / N-21
Biological Classification
267297
Lichens indicate $\text{S}{{\text{O}}_{2}}$ pollution because they
1 show association between algae and fungi.
2 grow faster thanothers.
3 are sensitive to $\text{S}{{\text{O}}_{2}}$.
4 flourish in $\text{S}{{\text{O}}_{2}}$ rich environment.
Explanation:
(c) Lichens are formed by symbiotic relationship between algae or cyanobacteria and fungi. Lichens typically grow in harsh environments most lichens, especially epiphytic fruticose species and those containing cyanobacteria, are sensitive to pollutants. Hence, they have been widely used as $\text{S}{{\text{O}}_{2}}$ pollution indicator organisms.
267294
In some viruses, RNA is present instead of DNA indicating that
1 their nucleic acid must combine with host DNA before replication.
2 they cannot replicate.
3 there is no hereditary information.
4 RNA can transfer heredity material.
Explanation:
(d) Viruses are defined as infectious nucleoproteins. A complete virus particle is called virion whose main function is to deliver its DNA or RNA gesnome into the host cell, so that genome can be expressed by the host cell. In a particular virus either DNA or RNA is genetic material, never both are present in a virus. Hence, viruses are:
(i) Double stranded DNA or ds DNA - Hepatitis B
(ii) Single stranded DNA or ss DNA - coliphage
(iii) Double stranded RNA or.ds RNA - Reo virus, wound Tumor virus
(iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)
NCERT Page-26 / N-20
Biological Classification
267295
T. O.Diener discovered a new infectious agent that was smaller than viruses and have the following characteristics.
(i) It causes potato spindle tuber disease.
(ii) It has free RNA.
(iii) Molecular weight of RNA is low.
Identify the infections agent.
1 Prions
2 Viroids
3 Lichens
4 Mycoplasma
Explanation:
(b) Viröids cause potato spindle tuber disease (PSTV), chrysanthemum stunt, citrus exocortis, cucumber pale fruit etc. They cause persistent infections, i.e., never recovered.
NCERT Page-27 / N-21
Biological Classification
267296
The symbiotic association between fungi and algae is called
1 lichen
2 mycorrhiza
3 rhizome
4 endomycorrhiza
Explanation:
(a) The symbiotic association of fungi and algae is called Lichen. In lichen, there are two components i.e., algal partner called phycobiont and fungal partner called mycobiont.
NCERT Page-27 / N-21
Biological Classification
267297
Lichens indicate $\text{S}{{\text{O}}_{2}}$ pollution because they
1 show association between algae and fungi.
2 grow faster thanothers.
3 are sensitive to $\text{S}{{\text{O}}_{2}}$.
4 flourish in $\text{S}{{\text{O}}_{2}}$ rich environment.
Explanation:
(c) Lichens are formed by symbiotic relationship between algae or cyanobacteria and fungi. Lichens typically grow in harsh environments most lichens, especially epiphytic fruticose species and those containing cyanobacteria, are sensitive to pollutants. Hence, they have been widely used as $\text{S}{{\text{O}}_{2}}$ pollution indicator organisms.
