Biology - characteristics of living organisms

topic 1

what acronym does MRS C GREN stand for

Movement, Respiration, Sensitivity, Control, Growth, Reproduction, Excretion, and Nutrition

if an organism does not carry out all of the life processes of MRS C GREN what does this mean?

the organism is either dead or non-living

Why is nutrition necessary?

organisms must obtain food to provide energy.

why is energy necessary?

Energy is necessary to carry out life processes e.g movement, respiration and excretion.

How do plants get nutrition?

plants use sunlight, carbon dioxide and water to produce oxygen and glucose in the process of photosynthesis.

What organisms are autrotrophic?

plants, some bacteria and algae.

What organisms are heterotrophic?

animals, most bacteria and fungi

How do animals get nutrition?

Animals consume other living organisms in order to obtain the energy they require.

What happens through the process of digestion in animals?

they break down larger complex molecules into simpler molecules through the process of digestion.

what is respiration?

respiration is a chemical reaction carried out in all living organisms.

what happens during respiration?

energy is released from glucose either in the presence of oxygen (aerobic respiration) or the absence of oxygen (anaerobic respiration)

What products are produced from the reaction of respiration?

carbon dioxide and water as waste products.

what form is energy transferred in?

ATP

what is the equation for aerobic respiration?

glucose + oxygen → carbon dioxide + water

what is excretion?

excretion is the removal of toxic materials and substances from organisms

what is excreted by animals?

carbon dioxide, water and urea.

what is excreted from plants?

oxygen, carbon dioxide and water.

What does the sensitivity of an organism refer to?

it refers to its ability to detect and respond to stimuli in its surroundings. Sensitivity is crucial for survival and adaptation.

what are the sensitivity responses in animals?

in humans, the nervous system provides a complex system of receptors, neurones and effectors which detect and respond to different stimuli using electrical impulses. The endocrine system, also allows a response to stimuli using chemical messengers, which travel in the blood, called hormones.

what are the sensitivity responses in plants?

in plants, reponses are controlled by chemicals and are usually much slower.

what is geotropism?

a plants response to gravity which causes the roots to grow down into the soil

what is phototropism?

a plants response to light which causes shoots to grow towards sunlight.

what is control?

living organisms must control their internal environment in order to keep conditions within required limits. This is called homeostasis.

what is thermoregulation?

thermoregulation refers to the control of body temperature.

what are the homeostatic mechanisms in humans?

sweating, vasodilation, glucoregulation (control of blood glucose levels) and osmoregulation (control of water levels)

how do plants maintain a suitable temperature?

plants use transpiration to maintain a suitable temperature

how do plants lose heat?

water evaporates from the stomata on the underside of the leaf leading to heat loss

what is sexual reproduction

the male and female gametes fuse together. In humans, the male gamete is the sperm and the female gamete is the egg. In plants, the male gamete is in the pollen grains and the female gamete is the ovule.

what is the DNA of the offspring composed of?

it is composed of both maternal and paternal DNA

What is an example of asexual reproduction?

Mitosis

what is mitosis?

Mitosis is a process where a single cell divides into two identical daughter cells (cell division).

what single-celled organisms reproduce asexually?

bacteria or amoeba