endoparasitism
Cuscuta is a total stem parasite which is a good example of ectoparasitism. It is commonly found growing on hedge plants. It has lost chlorophyll and leaves in the course of evolution. It attaches and wraps itself around the stem of host plant and produces haustoria that gets inserted into the vascular system of host. The parasitic plant sucks all the nutrients from the host plant with the help of haustoria. Cuscuta is known to receive even the flower inducing hormone or florigen from the host.
The other relationships mentioned above are not seen in Cascuta.
Cuscuta, commonly known as dodder or strangle weed, is a parasitic plant that belongs to the family Cuscutaceae. It is a unique type of plant parasite that lacks chlorophyll and is unable to photosynthesize. Instead, it relies on other plants for its nutritional needs.
Cuscuta is considered an ectoparasite because it attaches itself to the host plant by winding its stem around the stems or branches of the host. It forms specialized structures called haustoria that penetrate the host's tissues to extract water, nutrients, and carbohydrates from the host's vascular system. The haustoria establish connections with the host's xylem and phloem, allowing the Cuscuta plant to directly obtain nutrients and water from the host plant.
Match List I with List II.
List I (Interacting species) | List II (Name of interaction) | ||
A | Leopard and a Lion in a forest/grassland | I | Competition |
B | A Cuckoo laying egg in a Crow’s nest | II | Brood parasitism |
C | Fungi and root of a higher plant in Mycorrhizae | III | Mutualism |
D | A cattle egret and a Cattle in a field | IV | Commensalism |
Choose the correct answer from the options given below
Match List I with List II:
List I (Interaction) | List II (Species A and B) | ||
A. | Mutualism | I. | +(A), O(B) |
B. | Commensalism | II. | –(A), O(B) |
C. | Amensalism | III. | +(A), –(B) |
D. | Parasitism | IV | +(A), +(B) |
Choose the correct answer from the options given below:
List I | List II | ||
A | Logistic growth | I | Unlimited resource availability condition |
B | Exponential growth | II | Limited resource availability condition |
C | Expanding age pyramid | III | The percent individuals of pre-reproductive age is largest followed by reproductive and post reproductive age groups |
D | Stable age pyramid | IV | The percent individuals of pre-reproductives and reproductive age group are same |
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)):
A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is