Official / Original Previous Year (Old) Solved Question Paper of GATE Biotechnology 2016 with Answer Key and Explanations as PDF. GATE BT aspirants can download the question paper as single PDF file for your exam preparation. Please feel free to inform us for any mistakes in the answer key provided.
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Official / Original Previous Year (Old) Solved Question Paper of CSIR Junior Research Fellowship (JRF) and National Eligibility Test (NET) Life Sciences (XL) Examination December 2015 with Answer Key and Explanations as PDF. CSIR aspirants can download the question paper as single PDF file for your exam preparation. Please feel free to inform us for any mistakes in the answer key provided.
Organisms living together in a community influence each other directly or indirectly under natural conditions. All the vital process of living such as growth, nutrition and reproduction requires such interactions between individuals in the same species (intraspecific) or between species (interspecific) These inter or intra relationships of individuals in a population or community of an ecosystem is called biological interactions or population interactions.
The interaction between organisms may not be always beneficial to all the interacting counter parts. Based on whether, the interaction is beneficial to both interacting species or harmful to at least one interaction species, the ecological of biological interactions are classified into two categories.
(I). Positive interactions
(II). Negative interactions
(I). Positive interactions:
In positive interactions, the interacting populations help one another. The positive interaction may be in one way or reciprocal. The benefit may be in respect of food, shelter, substratum or transportation. The positive association may be continuous, transitory, obligate or facultative. The two interacting partners may be in close contact in such a way that the tissues intermixed with each other; or they may live within a specific area of the other; or attached to its surface. Different types of positive population interactions are:
Similarities and Difference Between Oomycetes and True Fungi
Oomycetes, commonly called as water molds, are a group of fungi with distinct phylogenetic importance. Apart from its phylogenetic importance, Oomycetes are disreputable for their plant pathogenic properties. This group includes the notorious plant pathogen, Phytopthora, which cause late blight of potato, the major culprit in Irish Famine. Even though Oomycetes are traditionally included in the Kingdom Fungi, the current developments in the phylogenetic studies showed that Oomycetes are rather a controversial group which shows more phylogenetic lineage with photosynthetic organisms such as diatoms and brown algae. Morphologically Oomycetes are more allied to the Kingdom Fungi, however, in their phylogeny and physiological features they shows considerable difference from true fungi. Recent molecular studies using DNA sequencing confirmed that Oomycetes are closely related to algae than true fungi and with this modern evidence, the Oomycetes should be regarded as “colorless” algae rather than true Fungi. In this post we will discuss the similarities and differences of Oomycetes from true fungi which will help you to understand the phylogenetic importance of this group.
Similarities between Oomycetes and true Fungi
Ø Oomycetes and true fungi are eukaryotes
Ø Both Oomycetes and true fungi, the vegetative plant body composed of mycelium formed by organized hyphal networks.
Ø Both Oomycetes and true fungi have heterotrophic mode of nutrition.
Ø Both groups obtain nutrients by absorption
Ø Both groups are devoid of chlorophyll pigments and hence they cannot do photosynthesis.
Ø Both groups include parasitic members
Ø In both groups, cell possess cell wall (the chemical nature of cell wall varies)
Ø Both groups includes flagellated structures (flagellated structures are absent in the higher groups of true fungi)
Ø Both groups undergo sexual reproduction
Ø Both groups produce spores as a mode of reproduction
Difference between Oomycetes and True Fungi
1. Neighboring taxonomic group: Based on the phylogenetic analysis with 18S rRNA, oomycetes are more related to Heterokontae which contain diatoms and golden-brown algae
2. Hyphal architecture: Aseptate and coenocytic tubular hyphae
Pits are the characteristic depressions on the cell walls of plant cells. They act as the channels for the transport of water and minerals between adjacent cells. Pits of two neighboring cells are usually located opposite to each other and these opposite pits together are called pit pair. Each pit has a cavity called pit cavity. Pit cavity opens internally to the lumen of the cells. The pit cavities of a pit pair are separated by a thin membrane called pit membrane. Pit membrane composed of the middle lamella and the primary cell wall of corresponding cells.
What are primary pit fields?
Pits of primary and secondary cell wall show considerable differences. Well organized pits can be seen on the secondary cell wall. Pits of primary cell wall look like depressions on the cell wall. These depression like pits on the primary cell wall are called primary pit fields or primordial pits or primary pits. The cells with only primary cell wall, such as the parenchymatous cells of meristem, have only primary pit fields.
The sectional view of a primary cell wall with primary pit fields looks like ‘beads on string’ like appearance. This is because; the primary pit fields are formed as depression on the primary cell wall, moreover, the primary cell wall of primary pit fields is relatively thin than other portions. The wall of the primary pit field is traversed by many plasmodesmatal canals. Plasmodesmata provide cytoplasmic connectivity between adjacent cells. Through plasmodesmata, the protoplasm of living cells are interconnected.