6. ORGANISMS AND POPULATIONS
2020
SAY
1. Choose the
correct answer: (1)
An organism that has the ability to concentrate its urine is:
(a) Desert Lizard (b) Seal
(c)
Flamingo (d) Kangaroo rat
ü Answer:
(d) Kangaroo rat
2. Analyse the
following table showing population interaction: (3)
|
Species A |
Species B |
Name of interaction |
|
+ |
(i) |
Commensalism |
|
+ |
+ |
(ii) |
(a)
Identify (i)
and (ii).
(b)
Define (ii).
(c)
Give an example
of commensalism.
ü Answer:
(a) i. 0 ii.
Mutualism.
(b) Mutualism is the interaction that confers
benefits for both interacting species.
(c) Orchid and Mango tree / Grazing cattle and egret
etc.
2020
MARCH
1. Fill up the
blank suitably. (1)
Mortality: No. of deaths in the population during a given period.
..........................: No. of births in the population during
a given period.
ü Answer:
Natality.
2. Identify the
types of population growth noted in the graph as 'A' and 'B'. (2)
ü Answer:
A= Exponential growth / J- shaped growth curve.
B= Logistic growth / S- shaped growth curve.
3. Given below are
examples for some ecological/population interactions. Place them under suitable
columns provided below. (3)
a. Abingdon
tortoise and goat.
b. Cuscuta and
host tree.
c. Fig tree and
wasp.
d. Algae and fungi
in Lichens
e. Belanus and Chathamalus bemacles
f. Lice on humans.
|
Competition |
Parasitism |
Mutualism |
|
· |
· |
· |
|
· |
· |
· |
ü Answer:
|
Competition |
Parasitism |
Mutualism |
|
· Abingdon tortoise and goat · Belanus and Chathamalus bemacles |
· Cuscuta and host tree · Lice on humans |
·
Fig
tree and wasp ·
Algae
and fungi in Lichens |
2019
SAY June
1. Differentiate
natality and mortality. Write the alphabets used to indicate natality and
mortality. (2)
ü Answer:
Natality: It is the number of births in a population during a
given period.
Mortality: It is the number of deaths in a population during a
given period.
Natality is indicated by the letter B.
Mortality is indicated by the letter D.
2. Name the
interaction between sea anemone and clown fish. Justify your answer with
suitable explanation. (2)
ü Answer:
Name of the interaction: Commensalism.
Clown fish protection from predators because
predators stay away from the stinging tentacles of sea anemone. But sea anemone
does not get any benefit from clown fish.
2019
MARCH
1. Match the
columns (A) and (B): (2)
|
(A) |
(B) |
|
(i) Mutualism (ii) Predation (iii) Commensalism (iv) Competition |
(a)
An orchid
growing on a tree trunk (b)
Gauss's
Exclusion Principle (c)
Biological control (d)
Derives
nutrition from the host organism (e)
Mycorrhizae |
ü Answer:
|
(A) |
(B) |
|
(i) Mutualism (ii) Predation (iii) Commensalism (iv) Competition |
(e) Mycorrhizae (c) Biological control (a) An orchid growing on a tree trunk (b) Gauss's Exclusion Principle |
2. Observe the
flow chart given below: (2)
a. Name the
processes represented as A and B.
b. If 'Nt' is the
population density at time t, then write down the population density equation
at time t + 1.
ü Answer:
(a) A= Mortality (D) B=
Emigration (E)
(b) Nt + 1 = Nt + [(B + I) – (D + E)].
2018
SAY June
1. A population
has certain attributes that an individual organism does not. What are they? (2)
ü Answer:
Natality, mortality, sex ratio, age distribution,
population density.
2. Parasites
evolved special adaptations to live on host. What are they? (2)
ü Answer:
Ÿ High reproductive capacity.
Ÿ Presence of suckers.
Ÿ Digestive system absent.
2018
MARCH
1. Under
unfavourable conditions many zooplanktons species in lakes and Ponds are known
to enter a stage of suspended development. Name that stage. (1)
ü Answer:
Diapause.
2. The following
graph shows two types of pollution growth curves. (3)
a. Name the growth
curves.
b. What does K
stand for?
ü Answer:
(a) Exponential (Geometric) growth curve and Logistic
(Sigmoid) growth curve.
(b) Carrying capacity.